Nitrogen purged binoculars
Binoculars in the higher segment of the market are made completely airtightonce they have been purged with dry, dust-free nitrogen. This procedure guarantees that the binoculars remain free of dust and moisture. After purging with nitrogen, a small amount of residual air remains in the binoculars. Less residual air remains in more expensive binoculars than in cheaper ones.
The binoculars can be filled with nitrogen at a slight overpressure in order to increase the water density, which is a great advantage in many cases. But also binoculars without overpressure are hermetically sealed to guarantee excellent long-term performance.
Binoculars can also be filled with argon instead of nitrogen and the effects remain beneficial.