Wheelchairs; wheelchair bases; power chair drive control systems comprised primarily of a joystick and electronic controller and circuitry to allow control over chair movement and speed; positioning products for wheelchairs and power chairs, namely, seats, seat supports, back supports, pelvic supports, pelvic positioning belts, knee stops/adductors, medial pads, trunk supports, lateral thoracic supports, upper body positioning belts, straps and harnesses, shoulder retractors, armrests, armrest pads, elbow support pads, armrest bases, calf supports, footplates, toe/ankle straps, calf panels, calf straps, leg foot boxes, shoe holders, foot boxes, ankle huggers, residual limb support, head, neck and shoulder positioning supports and pads, including mounting hardware and repair and replacement parts therefor