I bought the red/medium one to replace the much thinner resistance band that came with my Wii Active (it had torn and I didn't want to use it and have it snap in my face one day). I wasn't sure which one I needed, so I decided that the middle was good. When it came in, it looked like a short jump rope of sorts and it must prove to be quite a work out for those endowed with height (I'm rather short). It's not quite a BAND.. it's definitely more of a TUBE (I was hoping it would be a flat tube). This tube has resistance to it both on the tube itself and when pulling it. As such, it's not recommended to use it with bare feet because you're essentially stepping on tubes of rubber/stretchy material that will leave a mark, especially when you're trying to pull it over your head, which I haven't been able to accomplish. I got it to my shoulders. I guess that's why it's at the "medium" difficulty.