Develop fast twitch muscle fi bers. Explosive movements cannot be done with free weights or a pulley system because you are moving faster than gravity. Using Slastix™ as the form or resistance, the athlete trains without damaging expensive equipment. Unique 3 ring ankle strap allows Slastix™ to be connected to all key locations of the foot to allow nearly all leg exercises. Comes with 2 All-legs straps, 2 - 4' Slastix™, and 1 anchor.