This is a rare antique, patented light duty 1.5" capacity machinist C-clamp marked "CIN. TOOL CO." on one side of the frame, and "H 570" on the other side. It also has a raised cast lettering patent number on the wing part of the screw marked "PAT. 2016085 C.T. CO.", the patent number reflects a 1936 patent date. The H inside a circle represents the Cincinnati Tool Co. trade mark name HARGRAVE, which was often cast into various larger model C-clamp they manufactured. This clamp is used, but in very useable condition. It appears to have been painted red at one time, most of that paint is worn off. The screw threads are in great shape. The screw diameter is smaller than most they made, only 1/4", so we consider this clamp to be a light duty clamp, even though the cast iron frame is ample for this size. A hard to find quality made machinist clamp, as most we see have been damaged, this one had no rust and is in good straight condition!