Fits my FD mount lenses mostly well. Good price for an item not easily found unless you have a local use d camera parts dealer with an extensive collection.
I recently bought a vintage manual SLR Canon AE-1 camera, which came with 2 other lenses, a wide angle and a telephoto. Unfortunately, both of them did not have their original rear caps. In order to protect them, I searched Adorama for rear caps, and lo, I was able to find the rear cap that fit them both. Now I am able to use these different lenses "out in the field" knowing they're protected.