The first version of this helmet was designated the M23-27. The M34 was modified becoming heavier and the sides became shorter, though to the naked eye it is difficult to see the difference between the two. The oval badge to the front is made of bronze and painted matt black, this is the emblem of the "Orange-Nassau Royal Family". The ink stamp on the underside of the liner pad is that of the leather goods factory "De Volharding" of Amsterdam.
Above shows comparison between the M34 (Left) and M23/27 (Right)