I purchased these bands to use with P90X.  They seem to be well made - I did not feel like they were going to break while I was using them.  The handle can slip making them a bit uncomfortable to use, but that doesn't prevent them from doing the job.  I had never used bands before, but they were much cheaper than buying more dumbells....after a while, I decided I liked the dumbells better.  However; these are GREAT for when I am traveling and want to workout on the road.  I would highly recommend taking a Sharpie Marker and writing on each band the resistance level because unless you use them everyday, you won't remember which band is which.