3039-POLOLU 50:1 Micro Metal Gearmotor HPCB 12V
This gearmotor is a miniature high-power, 12 V brushed DC motor with long-life carbon brushes and a 51.45:1 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.
Key specs at 12Â V: 625Â RPM and 100Â mA with no load, 15Â oz-in (1.1Â kg-cm) and 0.8Â A at stall.