Using revolutionary phase change technology, the Ferno Aviation MIR Colling Vest, with cooling packs, will maintain a 59 degree (F) / 15 degree (C) tempature for up to 2 1/2 hours at 100 degrees (F) / 38 degrees (C). Perfect for use under body armor and in potentially dangerous high-heat enviroments. Cooling packs recharge in 20 minutes and are guaranteed to recharge for life. Tested and shown to be effective by both NASA and the U.S. Military. The entire system weighs 5 lbs. / 2.1 Kg. Available in Red or Woodland Camo. Vests & cooling packs sold together or separately.