An F-clamp, also known as a bar clamp or speed clamp and a "G-clamp", is a type of clamp. The name comes from its "F" shape. The F-clamp is similar to a C-clamp in use, but has a wider opening capacity (throat). This tool is used in woodworkingwhile more permanent attachment is being made with screws or glue, or in metalworking to hold pieces together for welding orbolting