The Klein Tools Cooling Fan (Cat. No. 60155) is designed for use with Klein Tools' hard hats and safety helmets with patented accessory mounts for easy attachment and removal. The dual-fan design forces outside air into the shell to push out stale hot air, facilitating cooling, Included long and short ducts can be configured 16 different ways for efficient airflow. Powered by a detachable, rechargeable lithium-ion battery (Cat. No. 29025) that can also charge other small USB devices.