Standard 4″ centerset Complete Re-Nu Stem.
This stem is commonly found in 4″ center Deck mount lavatory faucet. The most common application would have lever handles, if replacing both sides, buy one each of hot and cold stems. If your faucet uses cross handles, it should take two hot stems. Stem is 2 1/4″ long, 7/16″ smooth shank on stem, 22 spline.