An F-clamp with a specially designed head that fits into the slot of power tool guide rails. It is compatible with the Festool FS and Makita guide rail system and many others. The clamp has a plastic pad on the swivel shoe to protect the work surface.
Please check the clamp slot in your guide rail prior to ordering. The spigot is 11 mm wide by 7.5 mm thick and 60 mm long.