French A.N.P. M-51/M-53
The French A.N.P. M-51/M-53 was a slightly upgraded M-51, the main difference being the speech diaghram. It was used by the French military until it was replaced by the ARFA in the 1990's. This example was made sometime around 1953.
A.N.P. = Appareil Normal de Protection = "Normal Protection Device"