“Speakman” Tub Shower stem
This stem was used back in the 1920’s and into the 1930’s. Found in many in-wall tub and/or shower applications. Stem measures 4” long, shaft is 1/2” wide and has a square broach. This would have been found with a ceramic cross handle and a fairly shallow ceramic escutcheon behind it. Same stem for both hot and cold. Made in the USA. You’re not going to find this one at the big box stores!