CompCooler Backpack Full Body Cooling System, Full Body Cooling Performance, 3L Freezable Detach Bladder, Long Cooling Time, Underwear Design.Compcooler Backpack Full Body Cooling System (BFBS) is made up of Backpack Ice Water Circulation System and Full Body Liquid Cooling Garment. BFBS circulates cold water and continuously flow around body, legs and arms, keep user full body cool and comfortable in hot conditions. Backpack system includes 3L quick release bladder, 7.4V mini pump, 2200mAh battery and quick fitting. Base layer full body cooling garment with micro-tubing embedded provides better cooling performance. User may expect long time and extreme cooling feeling from 3L QR bladder, easy to replace and extend cooling time. Blue Stretch liquid cooling vest (Dark blue and Black liner) provides better air permeability and quick cooling performance, 3-6 hours cooling from 3L frozen bladder, 2-4 hours from ICE cubes, 7.4V 2200mAh rechargeable battery provides up to 10 hours operation. Cooling temperature range 36°F-68°F (2°C-20°C), Noise: 48dBA, Vest size: XS/S, L/2XL, 3XL/4XL, vest has 5-10 % stretch expansion by fabric (10cm/4" Max) to keep body fit. Ambient 0°C-60°C (32°F-140°F).This model is good for underwear application.Features:Extreme Cooling Performance 36°F-68°F, Well-distributed Four Zones Liquid Cooling Channel, Evenly Full Body CoolingComfortable Skin Cool Feeling, Dark Blue with Soft Stretch Air Permeability Mesh Liner, Soft Micro Tubing Embedded on the liner, No skin scratch feelingFull Body Cooling Vest, Body Fit Underwear Design, Front Zipper, 5-10% Stretch Expansion, with or without Hoodie Assembly3L Freezable Detach Quick Release Bladder, Quick Body Cooling, Easy to Replace and Extend Cooling TimeSafety and Healthy, Clean ICE Water Circulation for Body Cooling, 100% Safe Physical Cooling, Friendly and Environmentally CompCooler Backpack Full Body Cooling System with 3L Detachable Bladder