What is written on the left side of the insert (or how many expositions it allows)? '120' (12) or '120 J' (15)? In former case - you've got a square holder, 12 images on a film. Deal with this, square is better anyway; if you don't believe in the holly square, trim while enlarging. In latter case - it's a square holder with a 645 insert, you'll get 15 square, overlapping images on a film; worth nothing, but you may call it art and get famous.