Solomark 2 Inch Narrowband 10nm Oxygen-iii Nebula Eyepiece Filter Recommended for use with telescopes of 8" aperture or greater for best results and for visual use only Eyepiece filter features high quality optical glass in a double-threaded, metal filter cell Completely blocks virtually all other visible wavelengths of light so views of nebulas are optimized For viewing many common nebulas-Reduces glare and light scattering Increases contrast through selective filtration-Anti-reflection coated to prevent glaring and ghosting