Wow, What a workout!!! I am out of shape so I started out using the green bands, which I think are made of a Latex type of material (so be cautious if you are allergic). I have not yet worked my way up to the other bands, but in testing them I can tell the resistance in them is a major difference. It will be a while before I make my way to the black (Ninja-as I call it) band. I did use the bands on my arms to work my upper body as well, even though the exercises I did were not described in the manual, they worked great to exercise the biceps, triceps, upper back, and shoulders. With a little imagination, this are the perfect workout for the full body for someone who travels or does not wish to have a house full of gym equipment that they may need use. I received this at a full promotional discount for my unbiased review in return for free products. ‪#‎BootyLoops‬ https://www.amazon.com/Booty-Exercise-Workout-Resistance-Workout/dp/B0150BQYLM?ie=UTF8&*Version*=1&*entries*=0