Our BOLT™ Safety Helmet Cooling Liner is designed to be activated by water and features microfiber technology to keep you cool on the jobsite. This liner can be quickly activated by running or submerging it under water for 30 seconds for full absorption. Wring out any excess water and repeat when dry. When activated, the cooling liner will wick away moisture and heat giving you up to 4 hours of cooling time. Designed to be compatible with MILWAUKEE® Safety Helmets, our Helmet Cooling Liner will provide long-lasting comfort with its soft, comfortable padding and is part of the BOLT™ Accessory System which allows our users to secure accessories simultaneously.