This kit was purchased to hang a banner from the Fancier Studio TB30 8ft x 10ft Backdrop Support System Kit. It works, but the peaks are a full inch apart when I press the banner against the background support system crossbar. I got around this by rolling the top of the banner about two inches and these clips hold it in place perfectly. The actual clamps are approximately 3.75 inches long end to end and open to a full 2.5 inches. If you want real grommets to be a clamping surface, you'll need a 3/8" smaller crossbar. For something extra, you can do like I did and wrap part of the top of the banner or backdrop around the crossbar and you'll be fine work.They're relatively strong for my purposes and the tips are actually self-adjusting, which is a nice feature.Also, the tips are made of a softer material than the clip so are less likely to scratch the surface, and the textured surfaces provide a secure grip .