Used: Metering 45 degree prism set-up for Rolleiflex TLR's
This is a two part kit - the adapter frame and a Russian made metering prism. The adapter frame will fit most Rolleiflex TLR's that have a removable WLF and then this prism will side into the frame - as will any other finder for Hasselblad V including the lupe finders. The prism is held in via ball detent, but its not very strong. Tape or a set screw is recommended.
The prism has a button on the side that turns on the metering. I have included a few pictures of what this set-up looks like on my 2.8F (which isn't included)