Rated at 19 volts, but works just fine at 12 volts. They have a built in 9.98693 : 1 (17577/1760:1) gear reducer, and a 3/16" output shaft. They have a 500 count encoder on the end of the motor. You multiply the 500 by 4 to get the full resolution in encoder ticks, so 500 X 4 X 9.98693 is 19,973.9 encoder ticks for each revolution of the output shaft.

We've installed a circuit board for modular connection to the servo controller, and the motor power wiring, so it's just plug and play, no wiring for you!

Specifications:
Part Number: GM8224D309-R1
Rated Voltage 19.1
Maximum Continuous Torque: 2.6 Inch Oz (18.5 X 10-3 N-m)(before reduction)
Torque Constant: 2.47 Inch Oz (17.5 X 10-3 N-m) per Amp (before reduction)
Winding Resistance: 2.79 Ohms
No Load RPM at 19.1 volts: 10,000 RPM (before reduction)
Maximum RPM with SiTech ServoI Controller (24 volt Supply Before Reduction): 5,300
Maximum RPM with SiTech ServoII controller (24 volt Supply Before Reduction): 10,000
Maximum RPM with SiTech ServoI Controller (12 volt Supply Before Reduction): 5,300
Maximum RPM with SiTech ServoII controller (12 volt Supply Before Reduction): 6,282

Note: Divide RPM by 9.98693 to find the RPM of the output shaft
Note: Multiply Torque by about 9 for torque at output shaft.