This is a Symmons Temprol cap assembly – model T-12A-RP – a straightforward replacement part for your shower or tub valve.
If your old cap is cracked, stripped, or just not sealing right, this is the exact piece you need to get things back in order.

It's brand new and comes in original packaging, so you know it's fresh and untouched.

Made for bathroom use, obviously, and it's a genuine Symmons part so fitment is spot on.
No need to replace the whole valve assembly – just swap this cap and you're done.
It's a small part but it makes a big difference if yours is worn out.

Easy to install if you're handy, or a plumber can knock it out in minutes.

UPC is 671256728255 if you want to double-check.

Solid, reliable, and gets your shower working like new without a big expense.