Need help with shower cartridge

[Eightmarky]

Hi - my wife installed a shower system in her parents house about 15 years ago and doesn’t remember the brand. The components have no markings so I am looking for advice on how to track down a replacement cartridge. See photo. Thanks for any help.

 

[Geofd]

Bring that to a plumbing supply house they have usually seen everything

 

[breplum]

check: http://barrywalter.com/uploads/1/0/5/7/105704383/thermostatics_march_2023.pdf