Pictures are usually a help. Clamps tend to have the numbers 1911 and 1975. I am always getting the wrong clamp. A problem when there is not a good source of parts other than the DWC (Dead watchmaker corporation.) eBay sellers are also greedy and split the packages up. There are reasons mfgs put more than one in a package.
Getting parts watches for case clamps leads one further and further down the rabbit hole.
Had some luck with calibrating the fiber laser last night. If I can get it to cut through sheet metal, I might be able to make some clamps. The CO2 laser makes great movement rings.