Ergodyne - EGO12569 The Chill-Its 6700CT Cooling Bandana features advanced, PVA cooling technology for relief in extreme heat. It quickly activates for up to 4 hours of relief. Lightweight and low-profile, this comfortable cotton bandana is perfect for wear around the neck or under hard hats. A tie closure in the back allows an adjustable, snug fit on a variety of head sizes. This simple, effective and comfortable solution for heat stress prevention is similar to how sweat cools the body. It uses an external water source to draw heat away, helping to regulate body temperature while providing cool relief. When activated, this cooling bandana is comfortable and refreshing for even the hottest days of the year. It is also machine-washable.