This is a
Polaroid Tripod Adapter #261. You will need it for portrait format
photos on tripod as a kind of spacer with some of old folders of the
Pathfinder series, the 110, 120, 150 and 800. Theses have a
focussing knob under the bed of the camera that blocks a part of the
access to the mount screw.
The box. Note the spelling "adaptor" instead of adapter.
The box contains the mount and a short notice. It's cut out for a part of the knob.