Also useful for shadow box framing and for assembling L style / tray frames.
‘S’ shaped steel canvas offset clips with screw hole in one end and a flat plate on the other.
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. Zinc plated.
Approximate screw hole diameter: 3.5mm.