The Micro Gear Motors by Ever-power provides hobbyists and robotics enthusiasts with an inexpensive solution 
with their motor needs. The micro gear engine is capable of supplying up to 1650g. cm of torque; with this kind of a little size, these fantastic small motors hold their very own against complicated and demanding tasks. Have a look under the specifications tab to find out more on ordering 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 apparatus motor a simple task, requiring just two screws to add the assembly on your application.
All the micro steel gearmotors possess the same physical measurements, so one version could be very easily swapped for another if your style requirements change.
Long (9mm), 3 Drive Chain mm-diameter D-shaped metal output shaft.
4.5mm long, 1mm diameter back again shaft, ideal for optical encoders!