Use for repairing small holes, rips or voids between panels. The 3.5″ radius curve 100% Copper “spoon” supports your welding from behind. Use the Radius Curve where ever you have a curved surface like trunk decks, hoods, fins and more, plus you can position the spoon for indside or outside welding. The spoon acts as a heat sink to prevent warpage. The special mounting design permits setting the back offset left, right, and straight. Made in USA.