The Old NPC ProBack Let You Shoot Polaroid Peel-Apart Films with a Nikon SLR

Once in a while, you come across a photography contraption whose purpose or use eludes you. Some of the ones that occasionally still pop up on ebay and photography forums is the NPC Polaroid ProBack, a camera back that was designed to take Polaroid peel-apart instant films for checking exposure, lighting, and composition on the spot.