There are two types of FD mounts
FD/FL Breech-Mount (with a silver ring, you need to rotate the silver ring when attachment and removal), breech-lock mounts are identified by the silver ring
New-FD Bayonet Mount, bayonet mounts are identified by a red dot next to the lens release button

Here are the steps to install breech-mount version

1. Set your lens to smallest except for auto(bayonet mount only)
2. Rotating the Lock-Open ring of the adapter on the OPEN side
3. Line up the red dot with your lens and adapter ring(if yours is bayonet mount, just turn the adapter ring towards clockwise direction to make lens and adapter tight,then ignore the 4th step)
4. Turn your lens ring towards counterclockwise direction to make the adapter ring tight with your lens
5. Rotating the Lock-Open ring of the adapter on the LOCK side to engage the aperture closing pin

Operating the adapter

1. If you'd like to operate the lens aperture with the adapter; on your lens, set the aperture to the smallest opening and use the adapter ring
2. If you'd like to operate the lens aperture with the lens; place the adapter ring on the small aperture(Lock place) and control the aperture on the lens

1. please judge whether your lens could adjust the aperture there is only Nikon(G),also called AI(G) adapter ring has the aperture control ring, and is only for Nikon G lens,
   If you want to use nikon AI lens on this Nikon(G) adapter ring, it could be attached, but the aperture control ring could not be used as
   there is a pin on Nikon G lens that could move the aperture control ring but no on AI lens.
2. Some buyer mentioned could not adjust the aperture, actually this is because your lens does not have the aperture control function, If your lens does not have a manual aperture control ring, it will stop down to its smallest f/stop by default
3. Since there is no electronic contacted on our adapter ring, so could not transfer the aperture number to camera.