I purchased the Black Mountain Resistance Band Set to allow me to do strength training when I travel.  I had previously purchased another name brand set of resistance bands, but they had plastic D rings that would slip under strain.  The metal D rings and O rings on this set is a much improved upgrade for me.  The door holder and foot strap completes the accessories.  The set is easy to use and the bands are strong enough to meet the workout needs.  This is a high quality set or resistance bands.  The only negatives would be the work-out instructions are weak.  I downloaded a more comprehensive work-out guide for resistance bands that have better diagrams and more exercises.  Also, using multiple bands can be tricky.  It would be nice if there was a sleeve that would gather the bands when using three or more for safety and ease of use.  Overall, the quality for the price is outstanding.  I would recommend these to anyone who would like a good quality set of resistance bands.