Demon Zero RF D3O Protection Knee PadsUnisex Demon Zero RF Snowboard & Ski Knee pads, are super comfortable and not too bulky, they're designed to seamlessly fit under your snowboard pants. The D3O RF layer (Recycled Foam) is ingeniously combined with ESPRO polymeric material technology, resulting in a knee pad that's both durable and flexible. D3O Recycled Foams used on the knee pad D3O uses patented, patent pending, and proprietary technologies to make rate sensitive, soft, flexible