"These tubes are the best I have ever used.The quality on the bands surprised me. They feel durable, tough, and well made. What's more, each band is not only color coded, but labelled with the resistance "weight", so you don't have to memorize or lookup the values of each color! This is a small touch, but very helpful. And since you can stack them, you can mix and match easily to get the desired resistance as you progress in your strength, or change exercises. Love it!order another set for my daughter when she wears out the cheaper quality tubes she has been using."