Polaroid 545i film holder. If you are lucky enough to have some Polaroid film to use, you may not want to trust it to an old 500 or 545 back.  The rollers may have loosened up with age and use and won't spread the developer evenly. Iy might me a good odea to update to the 545i, the last Polaroid 4x5 film holder. Newer and made to improved tolerances, this will give you a better chance at success with that old film.  It can also accomadate Kodak Readyload or Fuji Quickload film packs. Just use the manual release button do the rollers don't close.  Ships via USPS Ground Advantage.