When hot weather operations demand protection from the sun without weighing you down, the Propper® IHWCU (Improved Hot Weather Combat Uniform) Boonie delivers. Built from a lightweight 5.5 oz 57% nylon / 43% cotton blend and sewn to military specification MIL-H-44105B, this boonie is engineered to block sunlight and keep your head cool when the heat is on. Metal vent holes in the crown provide airflow where you need it, while the adjustable chin strap keeps the hat secure during movement and allows for wearing around the neck when conditions change.