This is the pad that goes on the top inside of your S1 Lifer helmet.  It is compatible with both Mini Lifer, Lifer, Mega Lifer, Lifer Visor, Retro and Fullface helmets. It will stick to the top of your helmet with velcro and is thicker than the stock top pad for those who have some room in the top of the helmet to fill and want their helmet to not fit as deep.