2210-POLOLU 5:1 Micro Metal Gearmotor HP 6V with Extended Motor Shaft
This gearmotor is a miniature high-power, 6 V brushed DC motor with a 4.995:1 metal gearbox. It has a cross section of 10 × 12 mm, and the D-shaped gearbox output shaft is 9 mm long and 3 mm in diameter. This version also has a 4.5 × 1 mm extended motor shaft.
Key specs at 6 V: 6000 RPM and 120 mA with no load, 2 oz-in (0.1 kg-cm) and 1.6 A at stall.