This is a nice vintage 3.0" capacity C-Clamp with the cast steel design, marked "NO. 1430-3" MADE IN U.S.A. ADJUSTABLE" on the frame.  The C-frame appears to be chrome plates, about 90% intact. The maker is most likely Brinks & Cotton as this clamp frame casting matches another clamp we have marked B & C Co.. It's in very good usable 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.