This gearmotor is a miniature (24x10x12mm), high-power brushed DC motor with 50:1 metal gearbox, similar to Sanyo’s popular 12 mm gearmotors. These units have a 9mm long, 3mm diameter D-shaped output shaft.
Key specs at 6 V: 625 RPM and 100 mA free-run, 1.4 kg-cm and 1.6 A stall.