The KOR Trainer's patent pending Synchronized Mass Based Resistance System features the largest selectorized weight stack ever built. This 810 lb. laser cut weight stack is guided with high performance linear guide rods and bearings that deliver whisper smooth operation. It is precision tuned to deliver 405 lbs of quality (2:1) bilateral in-phase resistance and 202.5 lbs of extreme quality (4:1) unilateral in-phase resistance. This (2:1) bilateral/(4:1)) unilateral resistance ratio provides a synchronized resistance for even the most ballistic athletic movements. The fastest athlete will never out accelerate this innovative resistance system.