The Pix-o-mat 935 dates from the late 1960s and was made by Fendt for Montblanc. It uses standard D1 refills available at any stationery shop (LAMY, Schneider, Schmidt); Montblanc obtains its D1 refills from Schmidt but offers no green or red variants and charges roughly twice the price. The refill change is done exclusively by pulling out and inserting through the front opening; the writing instrument itself must on no account be opened, since reassembly will then no longer succeed. A binding price list for such vintage pieces does not exist; eBay auctions provide rough indications of current market values.