NiSi PRO Nano HUC UV ultra-thin filters adopt a double sided, multi-coating lens technology that employs high quality Japanese ultraviolet absorption optical glass. It assures high transmittance and highly smooth surface that avoids unnecessary reflection. The frame is constructed from Brass using highly accurate brass milling. The NiSi PRO Nano HUC UV has an exclusive creative U type Nano coating and a hardened waterproof coating. The UV filter is also useful as a general protective filter to leave on lenses at all times. Filters help to reduce dust and moisture from reaching your lens element and provide additional protection in case of drops or situations where scratching could occur.