MCUV: Reduce the UV-induced blue tone, blue-gray tone, increase the transparency, so that the picture quality more clearly. Applicable scenes: seaside, mountain, snowfield, open areas and so on.
CPL stands for Ciucular-Polarizing fliters, a kind of color filter, it is mainly used to reduce glare from water, glass, or any non-metallic surface, and eliminate the blue on the scene, making the scene more saturated.
ND lens: to reduce the amount of light entering the lens, get more control aperture...