This boonie hat is sewn to military specification MIL-H-44105B. Protect your eyes and keep out of the sun’s damaging rays with this military grade boonie Our eBay Store Propper Boonie – 100% Cotton This boonie hat is sewn to military specification MIL-H-44105B. Protect your eyes and keep out of the sun’s damaging rays with this military grade boonie. Vent holes on either side allow for air circulation and the adjustable chin strap ensures a secure fit. 100% cotton ripstop Sewn to military specification MIL-H-44105B Vent holes direct air away from head 2 3/8″ wide brim Adjustable chin strap ensures a secure fit