Concealable RPCM Cool Vests Designed after concealable personal body armor, the Concealable RPCM Cool Vest offers the unique advantage of being worn as an undergarment without being easily seen, even through thin outerwear. The Concealable RPCM Cool Vest's outer shell is constructed of White Twill material and utilizes the same phase change material as our other popular models. The Concealable RPCM Cool Vest will maintain a cool constant 59° F temperature for up to 2 1/2 hours, weighs less than 5 lbs., and recharges in minutes. Get an extra set of RPCM Cool Packs so you always have a set ready to use!