Neutral Density (ND) filters can reduce the intensity of light without appreciably changing its color Reduces brightness and cuts glare, increasing clarity of the moon, Venus, and bright double stars Helps conserve dark-adapted vision while viewing the lunar surface Helps reduce irradiation, which is the distortion at the boundary between light and dark areas, such as along the lunar terminator It offers you the freedom the create different neutral density freely 52% - ND2 Filter Material:Optical Glass Premium Material: Metal Frame 52% light transmission Provides a true Color image Threads on to any 1.25"- M28X0.6 threds eyepiece 25% - ND4 Filter Material:Optical Glass Premium Material: Metal Frame 25% light transmission Provides a true Color image Threads on to any 1.25"- M28X0.6 threds eyepiece 12.5% - ND8 Filter Material:Optical Glass Premium Material: Metal Frame 12.5% light transmission Provides a true Color image Threads on to any 1.25"- M28X0.6 threds eyepiece 6.25% - ND16 Filter Material:Optical Glass Premium Material: Metal Frame 6.25% light transmission Provides a true Color image Threads on to any 1.25"- M28X0.6 threds eyepiece 3.12% - ND32 Filter Material:Optical Glass Premium Material: Metal Frame 3.12% light transmission Provides a true Color image Threads on to any 1.25"- M28X0.6 threds eyepiece 1.56% - ND64 Filter Material:Optical Glass Premium Material: Metal Frame 1.56% light transmission Provides a true Color image Threads on to any 1.25"- M28X0.6 threds eyepiece Package Include: 1 x ND Filter