FOR USED PLATENS. Vertical Pipe Clamp, fast action, with V-Groove Swivel Pad. Will securely hold pipe, curved, narrow, or flat items. Clamp has 0 – 20 inch clamping envelope and 4-1/2 inch throat. Round Knurled boot fits 1-1/2″ square hole typical of some old, used (generic, no brand name) Platens. Simply drop this clamp into a square hole, tilt it back, slide the arm down until swivel pad contacts your work piece, and turn the screw. You will be securely clamped in seconds. Clamp can usually be loosened, and swiveled out of the way, when you are finished your welding or work process. Super simple and very fast clamping (and unclamping) process.