Size 12-1/2" Weight 40.00 Max. Opening 12-1/2" Min. Opening 0" Depth 4-1/2" Screw Dia. 1-1/8" Test Load 40,000 Lbs. Weight Per Box 40 Lbs. Frame is forged from high-strength, heat-treated steel. Large diameter screws are full length and hardened to prevent bending and protect threads. Clamp strengths exceed test loads shown. Conforms to Federal Specification GGG-C-406D, Type 1, Class B, heavy service.