In general automation applications where very small form factor gearboxes are needed, GE-20 gearboxes are the solution of choice. They can transmit up to 10 Nm (depends on ratio) and are suitable for motors up to 100W. Thanks to their lifetime lubrication with high quality synthetic grease, they're maintenance-free. With an outer diameter of only 40mm, and weighting around 300 grams for 1 stage models, and 400 grams for two stages models, GE-20 gearboxes are employed in very small machines.