Moon and Skyglow filters improves blocking of mercury-vapor light and higher transmission at critical hydrogen-alpha and hydrogen-beta lines. Bright light-polluted skies appear much darker and the contrast between object and sky is improved significantly. Moon and Skyglow filters allow maximum transmission of the important wavelengths of hydrogen-alpha and hydrogen-beta and doubly ionized oxygen most commonly emitted by nebulae. Views of galaxies and star clusters are also enhanced slightly. Available in 1.25″ and 2″ sizes.