This adapter was included with the camera that I purchased. It can be found on the internet easily and it is sold in Amazon and on E-Bay. It isn’t expensive.
Be sure to get the one that has two black view screens. One goes in the camera and one goes under the viewfinder.
What it does is allow you to use 35mm film in the Pentax 6×7, 120 film camera. The photo shown here is scanned at 1200 dpi and is really huge if you have a big computer screen and a fast connection.
It comes with two view screens and four metal nubs. Two are long and two are short. The long ones go on top and the short ones go on the bottom inside the camera.
A strip of film has to be attached to film in the spool, then that is wound into the spool before loading.
The other end of the added leader goes onto a salvaged take up spool. I’ve cut the leader film end to load into the slot. Another way is to copy how the manufacturer did it. If using tape, the film should stop short of the spool like it is on a used spool.
A spare 35mm negative holder was modified to accept this long format. I bought a small hacksaw but should have bought a coping saw, anyway, I have a drill press so the ends were drilled then bent out and filed. It is rough but can be perfected later.
I’m anxious to print some big prints!