Gosky 1.25 Crystalview Moon Filter for Telescope Eyepiece - Standand 1.25inch Filter Thread - Metal Frame - Optical Glass - Enhance Lunar Planetary Views - Eliminate The Street Light Smog Help to see the shadows in the craters and give improved definition of the surface of the Moon. Also helps with the problem of light pollution in area. In use the moon is easier to observe and does a good job of eliminating the street light smog from below our apartment in the city. Standand filter thread for 1.25" eyepieces and other accessories. Metal frame and made of optical glass Comes with a plastic box to keep it safe and clean when not in use.