The Irwin Record 135 Series Heavy-Duty Sash Clamps have a bar section of 32 x 6mm (1.1/4 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.1 x Irwin Record 135/3 Heavy-Duty Sash Clamp - 760mm (30in) Capacity.