... ice or refrigeration colloid, using air as cooling medium, Foldable and washable,military qualitySummer Air-cooled/ Air-condition Waistcoat/Vest=Specifications=1.Internal ... Grade controlling (1=low Grade, 2=middle Grade, 3=high Grade)2).LED light shows the battery condition3).Size:144 ... work time.5.No need ice or refrigeration colloid, using air as cooling medium, which is the most comfortable way ...