monocular
Hi type96,
Often offered for sale as Sniper spotting scopes, I know of no evidence for this, and suspect these were produced quite simply because for the same price/resource/time as a pair of binos, two soldiers can use these!
While these may not be common in the Americas, what your friend has is a German-manufactured monocular used by the Swedish army, and which have been sold off as surplus for a number of years now. Various manufacturers produced these under contract, as I understand it, for the Swedish army, which marks its equipment with one or more crowns (3 is quite common).
The monocular itself is Busch, Rathenow made, in a Hensoldt, Wetzlar case, but as mentioned makers vary.
The optic by itself goes from $40 (converted from European currency) upwards, depending on condition, rarity of maker, etc, with a matching case in fine condition from a rare maker someone might pay $150.
To find one WITHOUT Swedish army acceptance marks is an entirely different matter...
Hope this helps,
Jon