The Micro Gear Motors by Ever-power provides hobbyists and robotics enthusiasts with an inexpensive solution with their motor requirements. The micro gear engine is capable of supplying up to 1650g. cm of torque; with such a little size, these fantastic little motors hold their own against complex and demanding tasks. Have a look under the specifications tab to find out more on buying and torque/rpm figures.
Also available may be the MB7 Bracket, which is featured in one of the item images and will make mounting the gear motor a simple task, requiring just two screws to add the assembly on your application.
All the micro metal gearmotors have the same physical dimensions, so one version could be easily swapped for another if your style requirements change.
Long (9mm), 3 mm-diameter D-shaped metallic output 
shaft.
4.5mm long, 1mm diameter back again shaft, ideal for Auto Chain optical encoders!