Type: Cable Tester and high quality.The Card is named POST ( On Self Test) card too.It could display the error code by the result of POST.Then you would soon determine system, or blank screen.You can check your computer by our POST and don't have to open motherboard.LED displays and you can see Error code table in the user manual to check your computer.Item Type: Network Repair Tool KitSuitable type:PHOENIXBIOS4.01 TO 6.0 BOIS PC AND DESKTOPAMIBIOS6.24 AWARDBIOS4.51 BOIS PC AND DESKTOPBM T20 T21 T22 T23 A21 A22 A20 DELL640 4030 etc.colour:redMaterial:Metal + PCSize: 8060mm/3.152.36in (Approx.)LED Size: 50207mm/1.970.790.28in (Approx.)Package Contents:1*Computer Diagnostic Card1*English User ManualOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.