Cooling Hard Hat Gel Insert, INSERT ONLY, Heat Relief, Clearance, #6664 TechKewl Phase Change Cooling Crown Pad-CLEAR GEL INSERT ONLY - NO COVER - NO LINER Use additional inserts for continuous cooling relief. Comfortable 58F (14C) Phase Change Material sealed in high strength polyurethane. Include one (1) CoolPax Phase Change Cooling Crown Cooler Insert for Phase Change Crown Cooler (6622 - not included) No Cover/Liner