***** **********Best Quality Guranteed. *****UHC filters or light pollution reduction filters are designed to selectively reduce the transmission of certain wavelengths of light; especially those produced by artificial light*****Sky background is darker; and contrast of emission nebulae are noticeably improved; the perfect filter for viewing nebula from light polluted skies; or for boosting the contrast of nebula from dark sky sites*****Due to its ability to produce exceptionally sharp and clear images; this UHC filter is considered one of the most popular astronomy accessories; it can be used not only for celestial observations but also for astrophotography***** 1.25 '' barrel diameter simply attach to eyepiece cased in a sturdy transparent case; standard filter thread for 1.25" eyepieces and other accessories*****Optical glass lens; aluminum frame; significantly reduces light pollution; great for city and suburban observation