MAXPOWER Pack of 4 F Clamps, 300mm x 120mm Metal Welding Clamps Depth Heavy D...

Rail size 22 x 10.6mm. What is an F Clamp?. An F Clamp is a clamp that makes the shape of an F. This tool is mainly used in woodworking where it holds materials together until either glue or screwed make a more permanent fixture.

eBay