protractor WW2? any ideas?

[HxC]

Dear members, i found this protractor (i think that is the correct word?) it wears several markings, but i have no idea about it's age and maker. Probably some specialists here who can help me with it? It's a very heavy piece, solid brass i think. it wears these markings:
FLS 18 8918
A-C-H-HH
CASS 186

hope someone is here to give me some more info on this one. thanks in advance guys.
greetings, Matthias

[Mike TM]

A civil piece, I think, no KM.

regards
Mike

[HxC]

thank you sir, well i've send the picture to a collector here in Belgium and he answered me immediately, he says it's a piece from the reichswehr (1900's-1933) probably not a lot of members over here who know more about that (because it's not really kriegsmarine). But this ites should belong to the landforce and not kriegsmarine he stated, they seemed to be made in 2 different pieces; one with 5800 and one with 6400 as 'endnumbers' on the bow.. This would be the latest version, also used in WW2.. anyone? greetings, Matthias