This is high torque (20 kg.cm) DC motor fitted with a 75:1 metal gearbox. The gears are all steel and the outputshaft is 4mm diameter.  

Specifications

Voltage = 12V 

No load current = 250mA

Sall Current = 5 A 

Stall Torque = 20 Kg/cm

Motor Rated RPM = 133

Shaft Diameter = 4 mm

Motor Length (without shaft) = 53 mm

Motor Diameter = 25 mm