It's a simple device - heavy surgical tubing that can be doubled or tripled to increase the pull and a couple of grips to hold onto. It does help tone up the muscles that are used for pulling a bow and holding. Note that the Bowfit's draw starts light and becomes heaviest at full draw, in comparison to a compound bow (like most hunters shoot these days) which is heaviest as you start drawing and then gets lighter as the bow 'cams over.' 4 stars