It is a powerfull motor  fitted with a 34:1 metal gearbox. The gears are all steel and the output shaft is 4mm diameter.  The motor has extra rear shaft (on the high speed side, before the gearbox) which allow you to mount motor encoder for RPM counting and superior control.

Voltage = 6V 

No load current = 250mA

Stall Current = 6.5 A 

Stall Torque = 8.8 Kg/cm

Motor Rated RPM = 250

Shaft Diameter = 4 mm

Motor Length (without shaft) = 52 mm

Motor Diameter = 25 mm