A K'NEX battery motor with a 116cm (3.8 foot) tethered lead, powered by two "AA" batteries (not included). 36rpm approx.
Can drive two axles simultaneously. Housed in a clear plastic case, so you can see how it works.
The tethered lead allows you either to attach the battery holder to your model, or to hold the battery holder in your hand remotely from the model.View Video