A veritable poncho of oilskin hung from the bottom of it, alongside numerous straps. Ordinarily, oilskin was more for waterproofing than keeping the air out, but this helmet was designed to be able to fit multiple races. It meant that once fitted over the head, the straps would be tied tightly across the body of the wearer to seal the oilskin closely to the body so as to let as little air as possible escape and, more importantly, let only trace amounts of gas to enter the helmet.