Dual function oversized 9" diameter adjustable roller pad for comfort in use and proper alignment for both ab and back exercises.,Biomechanically angled seat with 5 gas-assisted adjustable positions is user-adjustable to acheive proper pivot point for exercise.,6-position adjustable leg pad/foot brace provides stability for users of all heights.Includes a 210 lbweight stack with a 310 lbweight stack option.,Works as a modular component on the ProDual 3-Stack and 4-Stack Gyms.