Nikon BR-2A Macro Adapter Ring is a reversing ring. It allows you to mount a 52mm front thread lens in reverse on the PB-6 bellows or Nikon cameras, greatly increasing the macro reproduction range capabilities.

It also allows for automatic aperture diaphragm control with the PB-4 or PB-5 bellows when combined with BR-6 auto adapter ring and also AR-4 or AR-7 or AR-10 cable release together.

Here is a highlight of Nikon BR-2A, BR-3, BR-5 and BR-6 Adapter Rings:

• BR-2A: Acts as a reversing ring. It mounts a 52mm front thread lens in reverse on the PB-6 and Nikon cameras. This increases magnification and working distance.
• BR-3: Acts as the opposite of a reversing ring. It provide a 52mm thread for filters and other lens attachments with lens in reverse.
• BR-5: It mounts lens with 62mm thread (use with BR-2A together).
• BR-6: Allows for automatic aperture diaphragm control with the PB-4 or PB-5 bellows when combined with BR-2 or BR-2A macro adapter ring and also AR-4 or AR-7 or AR-10 cable release together.