45 RPM 12V DC geared motors for robotics applications. Very easy to use and available in standard size. Nut and threads on shaft to easily mount on chassis and internal threaded shaft for easy connection to wheel.

6mm shaft diameter with internal hole
125gm weight
3000RPM base motor
No-load current = 60 mA(Max), Load current = 300 mA(Max)
Same size motor available in various rpm

Torque - 3.8 kgcm