The Gerbing 7V Circulatory Cooling Vest's built-in water circulation unit brings the highest-quality cooling technology into a compact vest for better wearability and easy operation. It comes with a 2L bladder that provides 1-3 hours of cooling. The rechargeable battery provides up to 9 hours of liquid cooling through tubing embedded in a mesh liner. The mini pump circulates cold water continuously flowing throughout the vest, keeping it cool and comfortable in hot conditions.Features:Ergonomic cooling design, front zipper with adjustable sidesFeatures a 2L bladderTouch-button control with 3-speed settings7V 2,200mAh battery1-3 hours of cooling from using ice cubes9 hours maximum run time Gerbing 7V Circulatory Cooling Vest