Alstar 2" Moon Telescope Eyepiece Color Filter Kit with 3 ND Moon Filters(ND96-0.3 ND96-0.6 ND96-0.9) with 13% Transmission for Moon Viewing, 2 inch Eyepiece Accessory. Neutral density filters are excellent filters to reduce the overall brightness of an image to cut down glare while viewing bright astronomical objects through a telescope. These three ND moon filters are useful for splitting binary systems; comfortably observing the moon; or stacking with other planetary filters. ND filters retain true color balance of the objects being observed since all wavelengths are transmitted uniformly over the entire spectrum. Especially useful for large aperture telescopes through which the light of the Moon can be extremely overwhelming. This ND96 neutral density filter allows 13 percent of the visible light to pass through; Metal filter cell threads directly into the 2 inch barrel of your telescope eyepiece