A.O. Smith AC motor. Made for Liftmaster door opener. 5/8" x 2/3/8"L keyed shaft. 1725-1425 rpm, 208-230v / 460v, 3 phase, 2.4 / 1.2 amps, 50/60 Hz, 1/2 HP. 56Y frame. Reversible. Base or front mount. Ball bearings. P/N: P56B71F21. 6 month warranty.