During our numerous polar trips, we learned that divers underestimate the heat loss under extreme conditions. Also, new technology allows divers to make longer dives and with this, the hypothermia factor enters the equation. Waterproof looked into this and created a series of accessories we tagged as "Polar Evoluted." The H2 5/10mm hood features a 10mm doubled layered protection in critical heat loss areas and glideskin seals for the neck and face. Waterproof H2 5/10mm includes the unique HAVS (Hood Air Venting System) which uses one-way valves to vent annoying air build-up in the hood.