What is this?

I found this below a 2nd floor master bathroom sink about as far away from the water heater as you can get. The home was built in 2015.

The cap says Wilkens Zurn Company.

https://www.nachi.org/forum/attachment.php?attachmentid=124866&stc=1&d=1456802101

Thank you.

what dis.jpg

Mixing valve for 2 handled tub faucet look up ASSE 1070. It’s required in IRC 2012

Assuming from the microscopic picture.

You nailed it Chuck. Thank you for the input. Now I am learning how they work.