Review on FramingSuppliesFast 1/8 Offset Mounting Canvas Z Clips for Picture Framing - #6 X 3/8 Pan-Head Screws Included - Pack of 100 by Amber Perez

Extra screw hole on the short side not very good for attaching the canvas to the frame. Some people might use it to screw it into the stretcher if there's a gap, but that's probably a bad idea. If you're using them for crafting or attaching other things, the second hole can come in handy, although there's only 1 screw per clip. If you plan to bend them a little to make them fit better, this can be done with pliers or a vise. This is a common problem with standard 3/4" deep frames when the glass is removed. Since glass or plexiglass is typically around 1.5-2.5mm thick, there is a gap between the blade and the clamp. A simple solution is to just cut out a piece of cardboard to place on the back of the canvas, poke a hole in the center to allow it to breathe and pull it tight, the cardboard will compress closing the gap and it is no thin paper+glue dust cover required.It also protects the back of the canvas.Another option is to take 1/8" clamps and put washers underneath or use thin metal straps that go into the subframes and the frame be screwed.but the cardboard method is cleaner.