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 28mm f/2.8, nFD 35mm f/2.8, nFD 50mm f/1.8 and nFD 24mm f/2.8 (http://shpws.me/S9cv)
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