Cooling Booney Hat Army ACU, Military Digital Green Camo, L/XL, #7021-A HyperKewl Evaporative Cooling Boonie Cap Classic hat for many uses. Tie fasten keeps hat on even in windy conditions. Provides 5-10 hours of cooling relief per soaking. Lightweight and Durable. Comfortable quilted nylon/cotton outer, w/polymer embedded fabric inner and water repellent nylon liner and fastener Size Guide: Head size in inches To Activate: Submerge in cool water 1-2 minutes or until desired consistency. Remove and gently wring or blot dry. May be reactivated by submering in water as needed. Care: Handwash using a mild detergent in warm water for 30 seconds. Rinse well, Gently wring or blot dry. Hand to dry. Be sure garment is completely dry before storing.