Looks like this is what you need for a ring style Air-Tite
https://air-tites.com/collections/model-y-air-tite-coin-holders-with-black-rings
The direct fit option is questionable. There is nothing at 50 MM exactly. The 51 MM would work but looking at the specs, the thickness seems off. The average poker ship is 3.4-3.5 MM thick and this Air-Tite allows for a thickness of 3.23 MM. Not sure how that would translate in the real world. It might work but the foam ring option might be easier.
https://air-tites.com/collections/direct-fit-air-tite-coin-holders/products/coinsafe-larger2-2-oz-round-51mm-coin-capsule-rc-51-r
Here is the full list of Direct Fit Air-Tites
https://air-tites.com/collections/direct-fit-air-tite-coin-holders
Hope this helps.