On the left is a Eckhardt Gas Mask that is dated 1937. I believe this style was used by the German civilians.
On the right is a German Gas mask that is dated October of 1936. The metal container is unit marked. The small brown round item between the metal can and gasmask is extra eyepiece lenses. More pictures of this gasmask and container are below.
The photograph on the left is a picture of how the gasmask would appear if worn. The photograph on the right is a date of October 1936 that is found on the inside of the gasmask.
The photograph on the left is a WAA 320 Waffenamt(German Army Weapons Agency) that is found on the inside of the gasmask. The photograph on the right is a picture of some miscellaneous manufacturers markings found on the filter of this gasmask.
These next two photographs show both the top and bottom of the filter element.
The photograph on the left is a picture of the metal gasmask container. In this picture, we can see that the container has a unit marking of P.H. 105. I believe that this marking indicates, Hannover police school item 105. The picture on the right is of the inside of this container. In this picture we can see the storage slot of the extra eyepiece lenses that were discussed above.