COP tester

This is the coil and ignition tester that I purchased recently (from some crazy website here). I have wanted one of these for quite some time but never bothered till now. I'm glad I did too! After changing the spark plugs I fired up the Porsche and ran around testing the coils and sure enough one was not firing. I swapped coils and got all 6 on line.
Now I need to test the BMW coils!