These tiny gearmotors are available in a range of gear ratios. All of the micro metal gearmotors have the same physical dimensions, so one version can be easily swapped for another if your design requirements change.
This gearmotor is a miniature (0.94" x 0.39" x 0.47"), high-power brushed DC motor with 50:1 metal gearbox, similar to Sanyo’s popular 12 mm gearmotors. These units have a 0.365"-long, 3 mm-diameter D-shaped output shaft.
This is a MLT-JR tracked robot platform and is equipped with 32mm motors, a motor controller, and Spektrum remote control. This is a rugged treaded robot platform. The robot handles up to 15lbs of additional payload and travels up to 220 feet per minute.