The Model MMP-TM55-12V GP52-308 DC gearmotor from Midwest Motion Products (Watertown, MN) accepts any 12-V DC source including battery power. The unit has a diameter of 2.14" and a length of 7.75", with a keyed output shaft 12 mm in diameter by 25 mm long. Mounting is accomplished with 4 face mount M5 threaded holes, equally spaced on a 40-mm-diameter B.C. Output is rated for 35 Nm continuous torque at 15 RPM, and 70 Nm peak. The unit requires 7.2 ampere at 12 V DC to generate its full load output torque. Optional 24- and 36-V windings are available.