This is a very nice, clean, heavy duty 4" capacity C-Clamp, marked "ARMSTRONG 78-434 DROP FORGED U.S.A.".  The frame, threads and the whole clamp are in very good condition, very little wear, not rusty or bent up, Very heavy duty, weighs 3.4 pounds and has an 8.25" long frame and the thickness at the clamp pad is 1" diameter, and the threaded screw is 3/4" diameter. The reach of the C frame is about 3.2" from the center of the threaded shaft to the edge of the frame. A very well made heavy duty C-Clamp by a well known tool maker, better known for quality automotive wrenches!