The Dynamixel AX-18A Smart Serial Servo from Robotis is a step up from the AX-12A servo providing twice the speed and 15% more torque. The AX-18A has additional feedback information such as speed, temperature, position and load.
This is a set of wheelchair motors and make great heavy duty robot motors. One left motor and one right motor. They are right angle gear drives with a release and electric brakes. They are 24VDC and the operating speed is 120 RPM.