prop stop/ reducer for folding prop

this is a prop stop and reducer combo for electric motors with a 3mm shaft, used to limit the travel of the props so they don't collide with each other or the aircraft.

https://www.amazon.com/Folding-Propeller-Different-Diameter-Airplane/dp/B07SMGQYJW/ref=asc_df_B07SMGQYJW?mcid=7ab16317d74d32c691c21ac630ee524e&hvocijid=17265772589533683905-B07SMGQYJW-&hvexpln=73&tag=hyprod-20&linkCode=df0&hvadid=721245378154&hvpos=&hvnetw=g&hvrand=17265772589533683905&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1027744&hvtargid=pla-2281435178298&th=1