The protective pads morph because they are made of a material called d3o. Engineered by a British company of the same name, d3o is an elastic polymer that tenses in response to quick movements. "It doesn't protect you as much as a hard helmet," cautions Swiss entrepreneur Jurg Ramseier, who released the first Ribcap last November. "It's for people who don't like to wear helmets." Van Enckevort, for example, uses a helmet in the park but prefers his 9.5-ounce beanie on the rest of the mountain.