I ordered this to put on my pendants that the catch or chain wouldn't go through. My older pendants have small bails or just O rings and the chain's that I have now wouldn't fit. I use to work in a jewelry store many years ago and would replace O rings with split rings but they aren't the greatest looking thing on a pendant if they are larger tnat 5mm. So I got a brainstorm and looked this up and it WORKS and is great.