cutting 3" flexwatt

[771subliminal]

Ok. I have some 3" flexwatt for something I am working on. I have always used 4" in the past. I know you must cut the 4" between the black lines. But I was told the three inch you don't have to. The four inch lines look like ][ the 3" looks like //. Can someone help me here?

you can cut anywhere on the strip and make it as long or short as your want, just dont cut across any of the black lines only between them.