The Chill-Its 6715CT Hard Hat Cooling Top Insert straps into hard hats to deliver four hours of cooling relief. The low-profile and lightweight liner pad features advanced PVA cooling technology for instant cooling without bulk or slime, making it comfortable to wear under hard hats. This hard hat liner pad fits most hard hats and safety helmets, easily and securely attaching to the suspension with two hook & loop straps. Heat-related illness continuously ranks among the top approx.