This overlay sits on top of a cushion with a removable pommel that helps prevent sliding. The pommel also provides leg abduction. Comfortable foam-padded pommel maintains pelvic neutrality. Keeps legs in abduction. Attached Velcro 6" pommel removes for easy transfer. May be used with or without cushion. Effective in any chair. Low-Shear I launderable outer cover reduces skin damaging friction.