This vintage heavyweight large sized C Clamp is marked WILLIAMS NO. 412 S DEEP THROAT CLAMP on one side. The other side is marked J.H. WILLIAMS & CO. DROP FORGED STEEL IN U.S.A. With the screw closed the opening is over 3 ½ inches. When fully opened the opening is approx. 12 3/8 inches. It measures overall closed approx. 19 ½ inches long, 8 ¾ inches wide and almost 1" thick on the ends of the C. From the screw to the C measures 5 3/8 inches. It has some paint loss, wear, stains, etc. It is well used in good condition for collecting, use or display. The Screw turns easily. It weighs almost 13 pounds. It will fit in a large Flat Rate Box which has room for more.