Custom Solid Seat Insert, 15" to 20" in width and depth, made of a ½" of HDPE (High Density Polyethylene), a foam module (Medium Package 1" Soft Sunmate on 1" Medium Sunmate), a zippered Black Neoprene (Rubatex) cover and secured by height/angle adjustable steel mounting hardware (standard duty 4ea. L-Brackets w/4 holes, 4ea. J-Hooks w/1 countersunk hole & 4ea. horseshoe clamps for 1" tubing). (T-Nuts installed to accept a pair of aluminum tracks for future mounting of Lateral Hip/Thigh Supports and Lateral Knee Supports)