This is a nice antique 2.0 inch capacity C-Clamp with the cast steel design, marked "S.H.C. 122" on one side and "MALLEABLE" on the other side of the frame. It is of a nice quality cast iron with a nicely finished frame casting. It's in very good useable condition with no rust, straight, not bent, good threaded rod. This type of C-Clamp is made of top quality steel and is heavy duty, so these could be used in metal working.  We assume this clamp was distributed by The Shapleigh Hardware Company, Philadelphia, PA. U.S.A..