This gearmotor is a miniature 24 x 12 x 10mm, low-current brushed DC motor with 9.96:1 metal gearbox, similar to Sanyo’s popular 12 mm gearmotors. These units have a 9.3mm long, 3 mm-diameter D-shaped output shaft.
Key specs at 6 V: 1300 RPM and 20 mA free-run, 0.1 kg.com (1.4 oz-in) and 0.36 A stall.