The Dragon D2 snow goggles have a medium fit & are designed & constructed to be compatible with a helmet. The frame will stay flexible in even the coldest conditions & the dual layer face foam & micro-fleece lining offer superior comfort & fit. Dragon's Super Anti Fog technology utilizes the same anti-fog chemicals used by NASA for spacecraft windshields & space helmet visors. the result is the strongest anti-fog known to man lasting twice as long before fogging when compared to competitors.