ProductFiles/150125/CertsReports/011CE WSCT

Report 5 Downloads 44 Views
v'?ir

ffiffi#ffiSffiifilffi8*H CE EMC TESTREPORT for mini-speaker MODEL:AK-M-YX011 TestReportNumber:WSCTo8l20335E lssuedDate:January05,2009 Issuedfor

Shenzhen Akunelectronicco..ltd Room711,Floor T,Shenfang Building, Huaqiang NorthRoad,Futian District,Shenzhen Cily,GuangDong Province,China lssuedBv: WORLDSTANDARDIZANO CERTIFICATION & TESTING CO..LTD. 1-2lF,Daohong Science&Technology Building, No.28ofTonggu Road, Nanshan District. Shenzhen.PRC TEL: +86-755-26996192 FAX:+86-755-26996253

NoE&: ThisEpaft sha not be rcprcdu@dexcebtin tult,withoutthe wtittenapprovalof l4/ortd Standadization Ceiification&TestingCO.,LTD.Thisdodrmentmaybe altercdor rcvied by V1/otd Standadization Ceftifrcation& TestiryCO.,LTD. petsnnelonly,and shatlbe notedin therevision sectionof thedocunEnf.ftre l-.sl /esuttsir aherepoftonlyapplyto thefesledsamp/e

Page1

Revision History Of Report Rev.

Issue No.

Revisions

Effect Page

Revised By

00

WSCT08120335E

Initial Issue

ALL

Sula Huang

Page 2 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

TABLE OF CONTENTS 1 2 3 4

TEST CERTIFICATION .......................................................................................... 4 TEST RESULT SUMMARY.................................................................................... 5 EUT DESCRIPTION ............................................................................................. 6 TEST METHODOLOGY ......................................................................................... 7 4.1. DECISION OF FINAL TEST MODE...................................................................................... 7 4.2. EUT SYSTEM OPERATION ................................................................................................. 7

5

SETUP OF EQUIPMENT UNDER TEST ................................................................ 8 5.1. DESCRIPTION OF SUPPORT UNITS ................................................................................. 8 5.2. CONFIGURATION OF SYSTEM UNDER TEST .................................................................. 9

6

FACILITIES AND ACCREDITATIONS................................................................. 10 6.1. FACILITIES ......................................................................................................................... 10 6.2. ACCREDITATIONS ............................................................................................................10 6.3. MEASUREMENT UNCERTAINTY...................................................................................... 10

7

EMISSION TEST .................................................................................................. 11 7.1. CONDUCTED EMISSION MEASUREMENT...................................................................... 11 7.2. RADIATED EMISSION MEASUREMENT .......................................................................... 16 7.3. HARMONICS CURRENT MEASUREMENT....................................................................... 21 7.4. VOLTAGE FLUCTUATION AND FLICKS MEASUREMENT.............................................. 24

8

IMMUNITY TEST.................................................................................................... 26 8.1. GENERAL DESCRIPTION ................................................................................................. 26 8.2. GENERAL PERFORMANCE CRITERIA DESCRIPTION................................................... 27 8.3. ELECTROSTATIC DISCHARGE (ESD) ............................................................................. 28 8.4. RADIATED, RADIO-FREQUENCY, ELECTROMAGNETIC FIELD (RS) ........................... 32 8.5. ELECTRICAL FAST TRANSIENT (EFT) ............................................................................ 36 8.6. SURGE IMMUNITY TEST .................................................................................................. 39 8.7. CONDUCTED RADIO FREQUENCY DISTURBANCES (CS)............................................ 43 8.8. POWER FREQUENCY MAGNETIC FIELD........................................................................ 47 8.9. VOLTAGE DIP & VOLTAGE INTERRUPTIONS ................................................................ 50

9 10

PHOTOGRAPHS OF THE TEST CONFIGURATION ............................................ 52 APPENDIX Ⅰ – PHOTOGRAPHS OF EUT ....................................................... 55

Page 3 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

World Shndardization Certification &Testing CO.,LTD World Standardizalion Safety andEMC Testiig Cenhe TESTCERTIFICATION minispeaker AK-M.YXO11 ShenzhenAkun electronicco., ltd Room711,Floor T,Shenfanq Burtdino. NorthRoad,FutianDistrict, - Huaqiang Shenzhen City,cuangDongProvince6hina ShenzhenAkun electronicco., ltd Room711,Floor T,Shenfana Butldtnq. Huaqiang NorthRoad,FutianDistrict. Shenzhen pfovince,6hina City,GuangDong N/A December 30,2008-January05,2009 DC5Vsupplied by PC

,

-

'

EN55022:1998+Al:2000+A2:2003 Cla6sB

)

'.rrr

EN 55024:1998+Al:2001+A2t2003 IEC61000-4-2r1995+A1 : 1998+A2: 20Ol lEc 61000-4-3i2002+A1 | 2002 IEC61000-4-4:2004 IEC610004-6:'1996+A1 : 2001 IEC61000-4-8:1S93 + A1: 2000

The aboveequipmenthas beentestedby World Standardization Certification& Testinq Co.,Ltd.And foundcompliancewith the requirements set fo(h in the technicalstandard; mentioned above.The resultsof testingin this reportapply only to the producusystem, whichwastested.Othersimilarequipment producethe sameresultsdue willnol necessarily

to production tolerance andmeasurement uncertainties.

p"r",)wf

/or / o(

(Chetiy Chen)

.trJoeLin) Approved By:-1222

447f

(Sula Huang) \J

Page4 this Epott shal not be reproducedd@pt in tull, wikut ke wnten appoval at WbndStffidatdjzatid Cetuicatjoh I festing CA., LTD.

2

TEST RESULT SUMMARY EMISSION Item

Standard

Result

Remarks

Conducted (Main Port)

PASS

Meet Class B limit

Radiated

PASS

Meet Class B limit

EN 61000-3-2 (2000) +A2(2005)

Harmonic current emissions

N/A

Meet Class D limit

EN 61000-3-3 (1995)+A1 (2001) +A2(2005)

Voltage fluctuations & flicker

N/A

Meets the requirements

EN 55022: 1998+A1:2000+A2:2003

IMMUNITY【EN 55024: 1998+A1:2001+A2:2003】 Standard

Item

Result

Remarks

IEC 61000-4-2: 1995 + A1: 1998 + A2: 2000

ESD

PASS Meets the requirements of Performance Criterion B

IEC 61000-4-3: 2002 + A1: 2002

RS

PASS Meets the requirements of Performance Criterion A

IEC 61000-4-4: 2004

EFT

PASS Meets the requirements of Performance Criterion B

IEC 61000-4-5: 1995 + A1: 2000

Surge

IEC 61000-4-6: 1996 + A1: 2000

CS

IEC 61000-4-8:1993 + A1: 2000

PFMF

IEC 61000-4-11: 2004

Note:

Voltage dips & voltage variations

N/A

Meets the requirements of Performance Criterion B

PASS Meets the requirements of Performance Criterion A PASS Meets the requirements

N/A

Meets the requirements of Voltage dips: 1) >95% reduction performance Criterion A 2) 30% reduction performance Criterion B Voltage variations: 1)>95% reduction performance Criterion C

1. The test result judgment is decided by the limit of test standard 2. The information of measurement uncertainty is available upon the customer’s request.

Page 5 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

3

EUT DESCRIPTION

Product

Mini-speaker

Brand Name

N/A

Model

AK-M-YX011

Applicant

Shenzhen Akun electronic co., ltd

Housing material

Plastic Engineering Sample. Mass Product Sample.

EUT Type Serial Number

N/A

EUT Power Rating

DC 5V supplied by PC

USB Cable

Unshielded with core, 0.8m

Product Sample,

Model Differences No.

Model Number

1

AK-M-YX011

I/O PORT TYPES

Q’TY

TESTED WITH

Mini USB Port

1

1

IPOD Port

1

1

Tested With

I/O PORT

Page 6 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

4

TEST METHODOLOGY 4.1. DECISION OF FINAL TEST MODE The EUT was tested together with the above additional components, and a configuration, which produced the worst emission levels, was selected and recorded in this report. The following test mode(s) were scanned during the preliminary test: Pre-Test Mode Mode 1: Charging

Conducted Emission Mode Emission

Mode 2: Play audio & Charging Mode 1: Charging

Radiated Emission

Mode 2: play audio Mode 3: Play audio & Charging

After the preliminary scan, the following test mode was found to produce the highest emission level. Final Test Mode Mode Emission

Conducted Emission

Mode 2: Play audio & Charging

Radiated Emission

Mode 3: Play audio & Charging

4.2. EUT SYSTEM OPERATION 1. Set up EUT with the support equipments. 2. Make sure the EUT work normally during the test.

Page 7 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

5

SETUP OF EQUIPMENT UNDER TEST 5.1. DESCRIPTION OF SUPPORT UNITS

The EUT has been tested as an independent unit together with other necessary accessories or support units. The following support units or accessories were used to form a representative test configuration during the tests. No.

Equipment

Model No.

Serial No.

FCC ID

Trade Name

1.

PC

DX2700

CNG714077P

N/A

HP

2.

Mouse

N/A

N/A

N/A

HP

3.

LCD Monitor

L1706V

CON74535YZ

N/A

HP

Shielded

Unshielded

1.5m

1.8m

HP

Unshielded

4.

Keyboard

SK-2800

435302-AA1

N/A

Data Cable

Power Cord

shielded

Unshielded

1.5m

1.8m

Unshielded 1.8m

1.5m

N/A

N/A

Note: 1) All the equipment/cables were placed in the worst-case configuration to maximize the emission during the test. 2) Grounding was established in accordance with the manufacturer’s requirements and conditions for the intended use.

Page 8 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

5.2. CONFIGURATION OF SYSTEM UNDER TEST

mini-speaker (EUT)

LCD MONITOR

PC

MOUSE

KEYBOARD

`

Page 9 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

6 FACILITIES AND ACCREDITATIONS 6.1. FACILITIES All measurement facilities used to collect the measurement data are located at 1-2/F, DaChong Science&Technology Building, No.28 of Tonggu Road,Nanshan District, ShenZhen.PRC The sites are constructed in conformance with the requirements of ANSI C63.4 and CISPR Publication 22. All receiving equipment conforms to CISPR Publication 16-1, “Radio Interference Measuring Apparatus and Measurement Methods.”

6.2. ACCREDITATIONS Our laboratories are accredited and approved by the following approval agencies according to ISO/IEC 17025. USA (The certificate registration number is 276008) FCC TIMCO (The certificate registration number is Q2001) Japan VCCI (The certificate registration number is C-2912, R-2662) Canada INDUSTRY CANADA (The certificated registration number is 46405-7700)

Germany

TUV (The certificate registration number is UA50138086-0001,UA50138086-0002)

China

EMCC (The certificated registration number is 080380) CNAS (The certificated registration number is L3732)

Copies of granted accreditation certificates are available for downloading from our web site, http://www.wsct.org.cn

6.3. MEASUREMENT UNCERTAINTY Where relevant, the following measurement uncertainty levels have been estimated for tests performed on the EUT as specified in CISPR 16-4-2: Measurement

Frequency

Uncertainty

Conducted emissions

9kHz~30MHz

+/- 3.59dB

Horizontal Radiated emissions Vertical

30MHz ~ 200MHz

+/- 4.77dB

200MHz ~1000MHz

+/- 4.93dB

30MHz ~ 200MHz

+/- 5.04dB

200MHz ~1000MHz

+/- 4.93dB

This uncertainty represents an expanded uncertainty expressed at approximately the 95% confidence level using a coverage factor of k=2 Page 10 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

7 EMISSION TEST 7.1. CONDUCTED EMISSION MEASUREMENT 7.1.1. LIMITS Class B (dBuV)

FREQUENCY (MHz)

Quasi-peak

Average

0.15 - 0.5

66 - 56

56 - 46

0.50 - 5.0

56

46

5.0 - 30.0

60

50

NOTE: (1) The lower limit shall apply at the transition frequencies. (2) The limit decreases in line with the logarithm of the frequency in the range of 0.15 to 0.50 MHz. (3) All emanations from a class A/B digital device or system, including any network of conductors and apparatus connected thereto, shall not exceed the level of field strengths specified above.

7.1.2. TEST INSTRUMENTS Conducted Emission Test Site 743 Name of Equipment

Manufacturer

Model

Serial Number Calibration Due

EMI Test Receiver

R&S

ESCI

100005

06/23/2009

LISN

AFJ

LS16

16010222119

04/02/2009

LISN(EUT)

Mestec

AN3016

04/10040

04/02/2009

NOTE: 1. The calibration interval of the above test instruments is 12 months and the calibrations are traceable to international system unit (SI).

2. N.C.R = No Calibration Request.

Page 11 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

7.1.3. TEST PROCEDURES Procedure of Preliminary Test The EUT and Support equipment, if needed, was set up as per the test configuration to simulate typical usage per the user’s manual. When the EUT is a tabletop system, a wooden table with a height of 0.8 meters is used and is placed on the ground plane as per EN 55022 (see Test Facility for the dimensions of the ground plane used). When the EUT is a floor standing equipment, it is placed on the ground plane, which has a 3-12 mm non-conductive covering to insulate the EUT from the ground plane. All I/O cables were positioned to simulate typical actual usage as per EN 55022. The EUT received DC 5V power from PC, and PC received AC mains(AC 230V/50Hz) through a Line Impedance Stabilization Network (LISN), which supplied power source and was grounded to the ground plane. All support equipment power received from a second LISN. The EUT test program was started. Emissions were measured on each current carrying line of the EUT using an EMI Test Receiver connected to the LISN powering the EUT. The Receiver scanned from 150kHz to 30MHz for emissions in each of the test modes. During the above scans, the emissions were maximized by cable manipulation. The test mode(s) described in Item 3.1 were scanned during the preliminary test. After the preliminary scan, we found the test mode described in Item 3.1 producing the highest emission level. The EUT configuration and cable configuration of the above highest emission levels were recorded for reference of the final test. Procedure of Final Test EUT and support equipment were set up on the test bench as per the configuration with highest emission level in the preliminary test. A scan was taken on both power lines, Line 1 and Line 2, recording at least the six highest emissions. Emission frequency and amplitude were recorded into a computer in which correction factors were used to calculate the emission level and compare reading to the applicable limit. The test data of the worst-case condition(s) was recorded.

Page 12 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

7.1.4. TEST SETUP

Vert. reference plane EMI receiver

40cm EUT

80cm

LISN

Reference ground plane

For the actual test configuration, please refer to the related item – Photographs of the Test Configuration. 7.1.5. DATA SAMPLE Freq. (MHz)

Q.P. Raw (dBuV)

Average Raw (dBuV)

Q.P. Limit (dBuV)

Average Limit (dBuV)

Q.P. Margin (dB)

Average Margin (dB)

Note

XX

36.01

31.18

60.00

50.00

-23.99

-18.82

L1

Freq. Raw dBuV Limit dBuV Margin dB Note Q.P.:

= Emission frequency in MHz = Uncorrected Analyzer/Receiver reading + Insertion loss of LISN, if it > 0.5 dB = Limit stated in standard = RAW (dBuV) – Limit (dBuV) = Current carrying line of reading =Quasi-Peak

Page 13 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

7.1.6. TEST RESULTS Model No.

AK-M-YX011

6dB Bandwidth

10 KHz

Environmental Conditions

22°C, 56% RH

Test Mode

Mode 2

Detector Function

Peak / Quasi-peak/AV

Test Result

Pass

Please refer to following diagram for individual

Page 14 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

The chart below shows the highest readings taken from the final data FREQ (MHz)

Q.P. RAW (dBμV)

AVG RAW (dBμV)

0.210

PEAK RAW (dBμV) 45.34

AVG Limit (dBμV) 54.28

Q.P. Margin (dB)

---

Q.P. Limit (dBμV) 64.28

NOT E

---

AVG Margin (dB) -8.94

---

0.640

37.47

---

---

56.00

46.00

---

-8.53

L1

1.075

37.78

---

---

56.00

46.00

---

-8.22

L1

1.940

37.72

---

---

56.00

46.00

---

-8.28

L1

2.780

35.71

---

---

56.00

46.00

---

-10.29

L1

18.040

44.51

---

---

60.00

50.00

---

-5.49

L1

0.210

43.21

---

---

64.28

56.00

---

-12.79

L2

0.321

36.48

---

---

61.11

51.11

---

-14.63

L2

0.645

34.78

---

---

56.00

46.00

---

-11.22

L2

1.940

34.11

---

---

56.00

46.00

---

-11.89

L2

3.320

33.10

---

---

56.00

46.00

---

-12.9

L2

18.040

44.18

---

---

60.00

50.00

---

-5.82

L2

NOTE: 1. L1 = Line One (Live Line) / L2 = Line Two (Neutral Line). 2. “---” denotes the emission level was or more than 2dB below the average limit, so no re-check anymore.

Page 15 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

L1

7.2. RADIATED EMISSION MEASUREMENT 7.2.1. LIMITS FREQUENCY (MHz)

dBuV/m (At 3m) Class B

30 ~ 230

40

230 ~ 1000

47

NOTE: (1) The lower limit shall apply at the transition frequencies. (2) Emission level (dBuV/m) = 20 log Emission level (uV/m).

7.2.2. TEST INSTRUMENTS Radiated Emission Test Site 966 Name of Equipment

Manufacturer

Model

Serial Number

Calibration Due

EMI Test Receiver

R&S

ESCI

100005

06/23/2009

Spectrum Analyzer

R&S

FSU

100114

04/21/2009

Pre Amplifier

H.P.

HP8447E

2945A02715

06/15/2009

JB3

A021907

06/10/2009

Bilog Antenna

SUNOL Sciences

Cable

TIME MICROWAVE

LMR-400

N-TYPE04

06/09/2008

System-Controller

CCS

N/A

N/A

N.C.R

Turn Table

CCS

N/A

N/A

N.C.R

Antenna Tower

CCS

N/A

N/A

N.C.R

NOTE: 1. The calibration interval of the above test instruments is 12 months and the calibrations are traceable to international system unit (SI). 2. N.C.R = No Calibration Request.

Page 16 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

7.2.3. TEST PROCEDURE Procedure of Preliminary Test The equipment was set up as per the test configuration to simulate typical usage per the user’s manual. When the EUT is a tabletop system, a wooden turntable with a height of 0.8 meters is used which is placed on the ground plane. When the EUT is a floor standing equipment, it is placed on the ground plane which has a 3-12 mm non-conductive covering to insulate the EUT from the ground plane. Support equipment, if needed, was placed as per EN 55022. All I/O cables were positioned to simulate typical usage as per EN 55022. The EUT received DC 5V power from PC, and PC received AC230V/50Hz power source from the outlet socket under the turntable. All support equipment power received from another socket under the turntable. Mains cables, telephone lines or other connections to auxiliary equipment located outside the test are shall drape to the floor, be fitted with ferrite clamps or ferrite tubes placed on the floor at the point where the cable reaches the floor and then routed to the place where they leave the turntable. No extension cords shall be used to mains receptacle. The antenna was placed at 3 meter away from the EUT as stated in EN 55022. The antenna connected to the Spectrum Analyzer via a cable and at times a pre-amplifier would be used. The Analyzer / Receiver quickly scanned from 30MHz to 1000MHz. The EUT test program was started. Emissions were scanned and measured rotating the EUT to 360 degrees and positioning the antenna 1 to 4 meters above the ground plane, in both the vertical and the horizontal polarization, to maximize the emission reading level. The test mode(s) described in Item 3.1 were scanned during the preliminary test: After the preliminary scan, we found the test mode described in Item 3.1 producing the highest emission level.The EUT and cable configuration, antenna position, polarization and turntable position of the above highest emission level were recorded for the final test. Procedure of Final Test EUT and support equipment were set up on the turntable as per the configuration with highest emission level in the preliminary test. The Analyzer / Receiver scanned from 30MHz to 1000MHz. Emissions were scanned and measured rotating the EUT to 360 degrees, varying cable placement and positioning the antenna 1 to 4 meters above the ground plane, in both the vertical and the horizontal polarization, to maximize the emission reading level. Recorded at least the six highest emissions. Emission frequency, amplitude, antenna position, polarization and turntable position were recorded into a computer in which correction factors were used to calculate the emission level and compare reading to the applicable limit and only Q.P. reading is presented. The test data of the worst-case condition(s) was recorded. Page 17 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

7.2.4. TEST SETUP

Test table & Turntable 1m ~ 4m EUT

Coaxial Cable

Power Cable

0.8 m

3m Filter Filter

Ground Plane

To Power

EMI Receiver

For the actual test configuration, please refer to the related item – Photographs of the Test Configuration. 7.2.5. DATA SAMPLE Freq. (MHz) xx.xx

Pk QP Pk QP Limits Read (dBuV/m) (dBuV/m) Margin(dB) Margin(dB) (dBuV/m) (dBuV) 31.57

Freq. Raw Data (dBuV) Corr. Factor (dB/m) Emiss. Level (dBuV/m) Limit (dBuV/m) Margin (dB)

---

-5.43

---

37.00

25.43

CF (dB) 6.14

= Emission frequency in MHz = Uncorrected Analyzer / Receiver reading = Antenna factor + Cable loss – Amplifier gain = Raw Data (dBuV) + Corr. Factor (dB/m) = Limit stated in standard = Emiss. Level (dBuV/m) – Limits (dBuV/m)

Page 18 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

7.2.6 TEST RESULTS Model No.

AK-M-YX011

Test Mode

Mode 3

Environmental Conditions

22°C, 55% RH

6dB Bandwidth

120 KHz

Antenna Pole

Vertical / Horizontal

Antenna Distance 3m

Detector Function

Peak / Quasi-peak

Test Result

Pass

Please refer to following diagram for individual

Page 19 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

The chart below shows the highest readings taken from the final data Freq. (MHz)

Reading(RA) Corr.Factor(CF) Measured(FS) (dBuV) (dB) (dBuV/m)

Limits(QP) Safe Margins Ant. (dBuV/m) (dBuV/m) H/V

Mark

30.00

27.39

4.96

32.35

40

-7.65

H

Q

83.57

46.50

-11.39

35.11

40

-4.89

H

Q

184.75

44.02

-7.66

36.36

40

-3.64

H

Q

202.06

42.48

-6.24

36.24

40

-3.76

H

Q

246.43

43.27

-6.58

36.69

47

-10.31

H

Q

674.55

31.65

4.28

35.93

47

-11.07

H

Q

30.00

37.14

1.47

38.61

40

-1.39

V

Q

79.24

48.26

-11.68

36.58

40

-3.42

V

Q

187.99

43.34

-5.87

37.47

40

-2.53

V

Q

219.92

45.20

-6.60

37.63

40

-2.37

V

Q

392.58

33.60

0.14

38.11

47

-8.89

V

Q

660.52

29.42

2.69

32.11

47

-14.89

V

Q

REMARKS:

1. P= Peak Reading; Q= Quasi-peak Reading A= Average Reading. 2. The other emission levels were very low against the limit.

Page 20 This report shall not be reproduced except in full, without the written approval of World Standardization Certification & Testing CO., LTD.

7.3. HARMONICS CURRENT MEASUREMENT 7.3.1. LIMITS OF HARMONICS CURRENT MEASUREMENT Limits for Class A equipment Harmonics Max. permissible Order harmonics current n A Odd harmonics 3 2.30 5 1.14 7 0.77 9 0.40 11 0.33 13 0.21 15
Recommend Documents