Red is correct. Technically, it is a diverter stem, not a faucet stem. The diverter stem is about 2.5x longer and takes water from 2 sources and flows them into one, or vice versa (as in going to two shower heads).
This is what I thought of first (drain wrench), but the "pegs" on yours seem to be on the inside instead of outside. Is it a plumber's tool?