Good Day,
Great find! You have a set of SwedishMauser m/96 night/low light sights. The "G" marked case stands for "Gevär" or rifle. Similar examples produced for the AG42 are stamped "AG" followed by a 3-4 letter/number combination production code. A similar concept night sight set-up was also produced for the Swedish M45 or "K" 9mm SMG's and are marked KPIST 1b.
The m/96 rear sight ladder must be removed for installation of the night sight and is held in place with the existing ladder pin. The front night sight slips over the existing barrel and front sight. It's almost certain the original fluorescent paint in the dots expired a while ago. The rifle sights are tough to find on the market. My set is marked "G 60H" but like yours, I have seen a "G 61H" marked set.
Regards,
Michael