Avoid crushing rusted galvanized pipes and nipples by using an internal pipe wrench instead of a standard pipe wrench. The General Tools 139B 1/2" Internal Pipe Wrench is ideal for installing and removing pipe nipples without marring, scratching or denting the pipe surface. It's also good for removing pipe plugs, broken pipe ends, and rusty fittings lodged inside pipes. Hex body can be turned by a fixed or adjustable wrench. Expandable knurled cams create a strong internal grip. The internal pipe wrenches are made from hardened steel and plated to help prevent rust plus meet U.S. Government Specification GGG-W643b for size and weight. Pipe size is marked on the wrench. The wrench length is 3-3/4 inch.