Canvas Offsets are ‘S’ shaped pressed steel with screw hole in one end and sometimes in the other.
For use when fitting stretched canvas into a frame with a shallow rebate. Also useful for shadow box framing and for assembling L-style frames. Many framers have found that they work well the other way round, to hold the sandwich in a frame when it is shallower than the rebate. Stick a piece of bumper under lip for a professional finish.