I was initially skeptical...that the garment cools continuously in temperatures as high as 120° F for up to eight hours. To my surprise, the helmet liner did keep my head cool during my two months of patrol." - Sgt Preston Pierce Chandler Police Dept. (AZ) The latest in Cooling Technology is now available from Seer Helmets! Our Helmet Cool Cap, S-7001, utilizes Hydroweave® technology to keep your head cool and comfortable during the hotest days! Our Helmet Cool Cap is one size fits all. It is slim and contoured to allow a smooth fit under your helmet. It is simple to use: 1) Soak your Helmet Cool Cap in a sink or container of cold water for 5-10 minutes, 2) Remove excess water by wringing out garment, 3) Towel dry the inner lining and outer shell.