See the attached photo. The stem is about two inches long. It's part of a bathroom faucet. There is no name on the faucet. The local suppliers had ones that were close but none that were exact.
All the faucets in the bathroom look to be a similar make. They have UPC stamped on them, although this one does not.
BTW, here is my shower faucet and I have same leak problem as named in the post:
Joe in Staten Island