It has 830 mark on the inside and Swedish controll stamp for silver on the outside.
With my 13 years in this hobby I've never seen a canteen ring with this pattern, nor have I ever seen one with the Swedish silver stamp. When Swedish stamps is on the outside, It's mostly on foreign stuff that's been controlled / or repaired then stamped.

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totenkopf3.jpg (27.55 KB, 195 downloads)