The Micro Gear Motors by Ever-power provides hobbyists and robotics enthusiasts with a cost effective solution with their motor requirements. The micro gear electric motor is capable of supplying up to 1650g. cm of 
torque; with such a small size, these fantastic small motors hold their very own against complex and demanding tasks. Have a look under the specifications tab to learn more on ordering and torque/rpm figures.
Also available is the MB7 Bracket, which is featured in another of the product images and can make mounting the apparatus motor a very simple task, requiring Drive Chain simply two screws to add the assembly on your own application.
All the micro metallic gearmotors have the same physical sizes, so one version could be easily swapped for another if your design requirements change.
Long (9mm), 3 mm-diameter D-shaped metallic output shaft.
4.5mm long, 1mm diameter back again shaft, ideal for optical encoders!