This is the Waterproof Drysuit H1 5/7mm Scuba Diving Hood with HAVS Without Bib Features: Durable Nylon 2 Neoprene Rubber Exclusive Hood Air Venting System (HAVS) HAVS System (double vent valves) Valves Eliminate Trapped or Build-Up Air from Regulator&';s Exhaust 7mm Double Layered Protection in Critical Heat Loss Areas 3-D Shaped Glide-Skin Seal Reflective Logo I-Span Super-Stretch Nylon Glued and Sewn Seams Bonded Hi-Quality Nylon Thread Waterproof&';s H1 5/7mm nylon-2 neoprene rubber hood with Waterproof&';s exclusive Hood Air Venting System (HAVS) is constructed with these scientific facts in mind and are proven to keep you warmer when you need it most. That&';s what Waterproof refers to as facing reality. Waterproof&';s exclusive HAVS uses double one-way valves to eliminate annoying trapped or build-up air caused by your regulator&';s exhausted air entering the hood. Hood features a 7mm double layered protection in critical heat loss areas. The hood has an anatomical 3-D shape for a great fit with glide-skin seals, reflective logo, I-Span super-stretch nylon for easy donning. All seams are glued and sewn with bonded hi-quality nylon thread for strength and durability.