On Waterproof 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 H1 5/10mm hood features a 10mm double layered protection in critical heat loss areas and glide skin seals for the neck and face. Waterproof H1 5/10mm includes the unique HAVS (Hood Air Venting System) which uses one-way valves to vent annoying air buildup in the hood.