Bushnell lens question

Recently, for some unknown reason, (probably the novelty factor), I bought a 20mm f3.8 Bushnell lens in Nikon F mount...apparently 1970's vintage.
Bushnell is well known for telescopes and binoculars, but I'd never seen a camera lens by them before.
I suspect that it is a re-badged lens, made by someone else... (similar to what Vivitar did in the '70's).
Anybody have the inside scoop on this?

There can't be that many different producers of those exact specs. A Google image search on 20mm 3.8 comes up with some variations - for example:
Does it look like yours?

If it has an 82mm filter thread than it is the same as the Vivitar. That was made by Kiron, and is a great lens.

If it does NOT have an 82mm filter thread then it's anyone's guess.

Hmmm... mea culpa.
It's actually a 21mm f3.8.

There is a 21mm f/3.8 that was rebadged by various entities, I have had one labeled "Asanuma" and another "Pro." For some reason I think the "Pro" brand is the ancestor of the "Promaster" rebadge line; not that they're the same lenses but the brand belonged to the same US distributor. Anyway, does it say something like "Lens made in Japan" on the bottom?

To my knowledge Bushnell was always a brand that imported products from Japan and other Asian manufacturers, including their binoculars, and yes they did sell lenses at some point. As far as I know, nearly all odd-brand lenses are contract manufacturing or rebadges, and the question is whether the same design appeared under multiple names (with cosmetic differences like the focus ring pattern), or whether it was built to specifications for one importer - such as the Vivitar Series 1 lenses, which are usually unique to Vivitar.

If it has an 72mm filter thread -- and I bet it does -- then it was also sold under the Vivitar & Soligor labels. That was made by Komine, and is a great lens.

If it does NOT have an 72mm filter thread then it's anyone's guess.

It does have a 72mm filter thread.
Thank you for the information, @xkaes and @reddesert!

"Bushnell" was a brand name originated by Bausch & Lomb for their binoculars. Over time the name spread to label many different things, made by many different companies.
It's interesting to learn about these manufacturers and their many mystery brands.