The PM4dx was issued in 1929. This carton is top opening with a tuck-in flaps to hold the valve below the top of the package. Inside the box is a shaped card liner. Inside the box was a piece of printed card defining the service and quality of the brand. The list of patent numbers and 1929 release date for the PM4DX places this carton design to late 1920s or early 1930s. The box is 70 mm square and 132 mm tall.