I am about half way through the P90X workout and have been using these straps.  So far they have held up well.  Clipping straps onto and off of the handles is quick and easy, so I can move from less to more (or more to less) resistance without hassle.  There is a short guide which tells you the relative resistance of each color band, so you can add up or subtract down to the resistance you want.  While I am sure there are better bands out there, I am also sure you would pay more for them.  This is a good product at a reasonable price.