The irwin record 135 series heavy duty sash clamps have a bar section of 32 x 6mm 114 x 14in 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