I've looked everywhere locally for a replacement shower stop and cannot find the right now. This is from an old shower (about 20 years). I've attached photos that show the size on top of a ruler.
The wide part is about 7/8" diameter, the narrow part is about 5/8". The hole in the center is about 3/8" diameter. It's plastic, and about 1/8" in thickness.
Any ideas? I'd really rather not replace the entire cartridge for this one small part, since that would involve taking out tile, etc....