Cartridge replacement help

[Rydon]

I have a cartridge that I need to replace for my hot shower valve. I can't seem to find it at any hardware store. Can you guys help me out with identifying this? I appreciate any hello I can get.

Edit: Tried to upload photos. But I can't find how to do this.

 

[Reach4]

See https://terrylove.com/forums/showthread.php?55180-Adding-pictures-or-attachments-to-post