What you get will be digital files, it is not a physical product.

1. In the package：Total 13 external spur gears(pinions): m1z9, m1z12, m1z15, m1z18, m1z21, m1z24, m1z27, m1z30, m1z33, m1z36, m1z39, m1z42, m1z45;

Total 10 internal and external spur gears: m1z33z44, m1z42z50, m1z54z64, m1z63z73, m1z72z82, m1z75z85, m1z81z92, m1z84z95, m1z90z101, m1z93z104

1. Explanationm1z9 – that means the gear’s normal module is 1 and the number of tooth is 9.m1z33z44 – the normal module is 1, quantity of internal teeth is 33 and number of external teeth is 44.

2. Size of gearIf you don’t have professional knowledge about gears, you can calculate the gear’s diameter simply:Diameter≈m*z+(0.5~5)mm.For example, the diameter of gear m1z45 is appr.: 1*45+2=47mm; diameter of m1z33z44 is appr.: 1*44+2=46mmIn this way, you can get the rough size of the gear, but it is not accurate enough for engineering.

You use the parts to assemble at least 10 sets of epicyclic gears that include 3 planetary gears. Any two or more gears can be assembled as transmission train. STEP and DXF format files are included. STEP format files can be used on 3d printer; DXF files is for laser cutting or CNC machining.The parts can be an educational toys for your children too.

One free epicyclic gear set of them can be downloaded here(m1z9z15z33z44): https://www.twothreed.com/download/epicyclic-gear-set-m1z9z15z33z44/

More about epicyclic gear set: https://www.tanerxun.com/planetary-gear-system/.html