6" Outside To Outside Measurement Caliper Legs, Forged Of Special Caliper Steel, Hardened & Tempered Bow Springs & Fulcrum Spools Assure Uniform Tension Without Side Play, Adjusting Screw Has A Self Seating Washer & Nut To Permit Quick & Positive Adjustment, Calipers Have Hardened Measurement Faces, Meets Government Specifications GGG-C-95.