The Elastitone have an extra sheath surrounding the band which inhibits you from overstretching them whilst also providing extra durabilty.This is partly why I purchased them.On receiving the bands and having used them I am more than happy with their quality and also the fact they have vastly increased my exercise possibilities without the need on many weights cluttering up the place.I find the range of movement and resistance they provide to be of better than with weight training.I received my order promptly and look forward to expanding my exercise routines with many other exercises in the future.I would have no hesitations in recommending the Elastitone bands.