Nikon PK-11 / BR-3 / BR-4 / BR-2 / E2 Analogue camera

The BR-3 is not a standard F→F adapter.

It is used when a Nikon lens is mounted inverted via a BR-2/BR-2A ring. The BR-3 plugs onto the rear mount of the inverted lens and converts it to a 52 mm thread, allowing 52 mm filters, lens hoods, or other 52 mm accessories to be mounted.

It is therefore a macro/reverse-mounting accessory, very interesting for those using the Nikon system for close-up photography.
various Nikon inversion/adapters rings
at least one other ring with Nikon F mount
components with chrome/black finish typical of Nikon accessories from the era
The BR-3 clearly recognizable from the front.

-Nikon f m
-Nikon BR-4
-Nikon PK11
-Nikon E2
-Nikon BR-3
-Nikon BR-2