Made of soft, lightweight knit fabric, a Cooling Arm Sleeve is designed to provide cooling relief as well as absorbing and wicking away sweat, and it also shields from the sun's UV rays and even protects against light abrasions. To activate the sleeve, prior to slipping it on the arm, one immerses in cold water then gently squeezes it. (Rehydration can be accomplished by merely pouring water on the sleeve without have to remove it.)