Use these hydraulic impact wrenches for tightening or loosening the most difficult fasteners, even in wet environments and sub-zero temperatures. These impact wrenches require a hydraulic power source to operate. They have the highest power-to-weight ratio among all impact wrenches, and produce less noise than air-powered impact wrenches. Hydraulic tools are self-lubricating and require less maintenance than other power sources, increasing tool life. Use impact sockets with your tool for best results.