The MiraCool hard hat pad fights heat stress and fatigue. It's what's inside that cools! MiraCool Cooling Crystals encased within a wide assortment of 100% cotton hard hat pad absorb and hold up to 1,000 times their weight in cool refreshing water. When hydrated and worn against head, neck, or body, the physics of cooling evaporation simply and naturally create cooling sensations that are carried throughout the body. Attach to the inside of your hard hat and stay cool all day. Neck shade option available. Hand washable. Sold by the each..