NITROGEN PURGED: Paired with a completely sealed chassis, nitrogen gas is used to purge air from the optic to help maintain internal fog-proof and waterproof capabilities. FULLY MULTI-COATED: Athlon Optics fully multi-coated glass gives you better light transmission with optimum brightness and true color across the entire light spectrum. WATERPROOF: Regardless of how heavy the rain is coming down or an accidental drop in the water, this sealed and gas-purged optic will remain waterproof.