Use the principle of parachute assisted reverse aerodynamics to build blazing sprint speed! As used by top pro football teams & world class sprinters. The Speed Parachute combines resistance and overspeed running during the run - the two key elements of speed training. The Speed Parachute provides resistance in the initial part of the run. During the run, release the Speed Parachute to initiate the overspeed phase. Feel the "shot out of a cannon" exhilaration! This combination increases your speed, explosiveness, acceleration, and stamina while improving running technique. Includes complete instruction program. Jumbo 85"x85" adds 40 lbs resistance.