This gear fits the Nikon 300mm f/4.5 IF ED AISlens.

It is designed specifically to fit this lens and is compatible with any standard 0.8 Module follow focus. They will sit 4-6mm high off of your lens for a low profile gear that looks elegant and fits into your current lens case. These gears do not have to be removed after each use although you can if you like. Each gear comes with a lifetime of support.

This gear is very specific to this version of the lens. The Nikon Ai-S, AI, and pre AI lenses look very similar. You can double check which version of the lens you have by serial number here:

http://www.photosynthesis.co.nz/nikon/serialno.html

300