The strongest C-Clamp made . Square-head screw has hardened point . Screw does not include handle--it must be tightened with a wrench . Extra long hub helps prevent springing even under great stress
From the Manufacturer
Armstrong Industrial Hand Tools have a heritage of Made in the USA since four brothers founded the company in 1890. This Armstrong brand product is built from premium materials and workmanship ensuring unequalled strength, toughness, and durability. Product Type: Heavy Duty Pattern C-Clamp Capacity Maximum (Inch): 4-5/8 Capacity Minimum (Inch): 1 Depth of Throat from Center of Screw (Inch): 2-7/16 Thread Size (Inch): 1-8 Length of Screw (Inch): 7-1/16 Minimum Proof Test (lbs): 20,000 Full Length Forcing Screw: No Finish: Black Oxide US Federal Specification: GGG-C-406d Replacement Forcing Screw: 95-389 Forcing Screw Threads: Standard V Threads.