These are heavy duty clamps with a bar section of 32mm x 6mm (11/4" x 1/4").The slide and head are guaranteed unbreakable and the slide is secured by a solid steel pin passing through one of the locating holes spaced along the steel bar. The steel mainscrew applies pressure quickly and smoothly through a fast acting, hard wearing rolled thread. Slides and heads are flat bottomed so that the clamp will stand without support.