These are just amazing little motors for their weight. With one at each of your four corners you are always guaranteed good traction and speed. These have a special long shaft with a "D" cut into it for the outer 10mm to ensure full engagement and proper spacing of our tank tread wheels.
18mm (0.7 in) long shaft x 3mm diameter
D shape on last 10mm (0.39 in)
100:1 gear ratio
Stall Torque: 14.9 oz-in (1073 g-cm)
Size: 0.47" x 0.39" x 1.24" (12mm x 10mm x 31.5mm)
Weight: 8.5 grams (0.31 oz)
200 RPM @ 4.5V