This gearbox increases the torque of an RS390 motor. 

To print:

• 2 - gears Gearbox-GearA
• 1 - Gearbox-Normal-Track-Gear (Optional Long-Track-Gear) 
• 1 - Gearbox-Bottom
• 1 - Gearbox-Top
   

Non print materials:

•  4 - M2 screws
•  1 - M2 26mm rod
•  1 - M2 16mm rod
•  1 - 15x10x4 bearing