Planetary gear set-There are 6 external gears and one internal gear. It is called epicyclic gear too. If you want to 3d print the models, suggest to use resin material.If you plan to use ABS/PLA material,it is best to modify the 3d models before printing.Ignore the OBJ and FBX files, they are just for cgtrader's requirement.
More about epicyclic gears: www.tanerxun.com/planetary-gear-system/.html