Clips are used to affix a stretched canvas to a frame. Also known as a “Z-Bracket” or "Z-Clip", this stepped metal hardware has a hole in both ends, through which a screw or nail is driven. One end of the bracket is fastened to the stretcher bar frame, the other to the back of the picture frame. Offset clips allow for artwork that is slightly larger or smaller than the depth of the frame rabbet to be fitted. They are also used to attach a canvas to a floater frame, or some people have used these to secure a camper canvas. Place your canvas in the frame and measure the distance from the back of the frame to the back of your canvas to determine the size needed.