Located under all the "AM/PM Kitchen" (bedroom) sinks in the house:
It adapts the 3/8 PEX output from the mixer valve to 1/4 PEX to the spigot. The thing that looks like a valve does not appear to do anything.
Sorry I don't have a banana for scale, but it is a fairly small item as you can tell from the 3/8 and 1/4 inch PEX at the top.
It also appears to be totally devoid of brand or part markings.
The faucet is probably Delta™, but because the valve and the spigot are separate items, it is possible that they are not the same brand.
I am looking for proper terminology, or a link to a product page, etc.
Or just informative observations.