UC-900-72" Alum Bar Clamp. Made in USA by the Dubuque Clamp Company, these aluminum bar clamps are lightweight, extremely rigid, and easy to adjust. The strong extruded bars measure 1-3/8" x 7/8" and have side walls nearly 1/8" thick for excellent resistance to bowing and twisting. The bar remains reliably straight under clamping force, so you can clamp work against it to prevent misalignment. The movable head has a spring clutch for fast adjustment on the notched bar, and the fixed head has a 1/2" diameter Acme-threaded screw for final tightening, with a large, easy-to-turn wing knob. 1000 lb load rating. Maximum opening capacity listed.