Gas mask & Cannisters marked "Gr 22 122" identification help?

[Haakon]

Hi. This gasmask and cannister was taken by a relative in 1945 in Norway and is in almost new condition as it have been stored very well.
It is marked "GR.II 122" on the bottom. Can anyone identify the unit? Trying to figure out where my relative "borrowed it" and who the previous owner was.

Thanks in advance for any assistance:-) (and sorry for the 90degree rotated picture)

[lebus12]

Perhaps you have a paper inside the canister ?
Better picture....

[Haakon]

Thanks for the photo edit:-)
Will have a search of the inside later today and revert.

[Haakon]

Only thing on the inside, besides its normal content, is an ink stamp mark «w.lohman»

[Kohima]

To me, ‘Gr.II’ suggests grosse II, or size 2, rather than a unit.