The Model No. MMP-TM55-12V GP52-022 DC gear motor from Midwest Motion can accept any 12-volt DC source, including battery power, says the company. It measures 2.14" in diameter by 7.25" long and has a keyed output shaft of 12 mm by 25 mm long. According to Midwest Motion's press release, easy mounting is accomplished with four face mount M5 threaded holes equally spaced on a 40 mm diameter bolt circle. The output of the gearmotor is rated for 2.5 Nm continuous torque at 209 rpm and 9.0 Nm peak. The motor requires 7.2 amperes at 12 volts to generate its full load output torque. Typical options include integral optical encoders, failsafe brakes, analog tachometers and planetary gearheads with standard ratios from 3:1 to 450:1 with standard or low backlash precison gearing available.