Planetary gearbox outer diameter: 9.9 mm
Motor specifications: 8 x10x12 mm (M10 motor)
Geared motor height: 19.5 mm (motor + gear box)
Output shaft: Gear with an outer diameter of 5.35 mm (11 teeth)
Reduction ratio: 1:171
Weight: 4 grams
Rated voltage: DC2.5V
No-load current: 40 MA
No-load speed: 92 RPM
Rated torque: 9.8 mN.m
Maximum torque: 37.2 mN.m

The following measures the motor speed under other voltages:
Voltage: DC3V Current: 42 MA Speed: 110 rpm
Voltage: DC3.7V Current: 48 MA Speed: 135 rpm
Voltage: DC4.2V Current: 52 MA Speed: 154 rpm
Voltage: DC5V Current: 58MA Speed: 180 rpm