Our Internal Pipe Wrenches are designed to rescue HVAC and plumbing professionals from broken pipe threads, plugs and fittings. The machined, heat-treated cams grab on to broken pipe fragments that have become lodged inside other pipe. The hex-shaped bodies are made from alloy steel and can be used with open- or closed-ended wrenches. Our Professional Series Wrenches conform to government specifications for size and weight. For 3/8 in. internal diameter applications. Ideal for professional use. Remove broken, threaded ends of pipe, pipe plugs and fittings. Machined, heat-treated cams. Hex-shaped design for use with standard wrenches. Size stamped on body. Conforms to government specifications (GGG-W643b).