Need help with this Auer gasmask canister

[xedos6]

I looked on the middle between the lenses inside but no RL number Just only a huge "G" and a number.

Inside the snout, when I screw down the black metal "microphone" thing, under that there's a "40" number which means 1940 I think. I think it was made before 1935 for Reichswehr, but in 1940 they changed or replaced the snout piece. The filter is not it's original, I have it from another mask..