I ordered this sizer because I have used the bracelet version of it for many years. Somehow never got around to getting the necklace version. It is everything it claims and is the very best way to get the internal diameter of a necklace. Use it for two purposes: have a customer bring a favorite necklace so that you can record its size for future purchases, and measure the inside diameter so that you can accurately describe a necklace in an online advertisement/listing. People really need to know this before ordering. The only downside is that it is not collapsible. Once you put it together, it stays together, taking up considerable space in the workshop. Small price to pay for this kind of convenience.