Astromania 1.25" Crystalview Moon Filter Metal filter cell threads directly into 1.25- inch telescope eyepiece barrels. Provides a brighter view than the 13 percent Moon filter by blocking less light - ideal for use with smaller telescopes. A specialty Moon filter especially useful for increasing contrast during waning and waxing crescent phases. Enhances the contrast of the moon and planets in photographic images Reduces bright glare reflected off the Moon and boosts contrast and resolution of lunar surface features.