This BETA product was designed to modify and adapt a FDn lens to use it with EF DSLR Cameras, along with Aperture arm for nFD 85mm f/1.8 (https://shpws.me/SlYP)
This product needs to be separated with a hobby knife.
For more aperture arms please visit the store main page:
https://www.shapeways.com/shops/lensmounts
Follow this link to see the tutorial:
https://youtu.be/Jiv1HAlwF68