Astromania 1.25" 90-degree Erecting Prism. This is an economical 1.25" 90-deg prism diagonal for astronomical telescopes and spotting scopes. With this 90-degree erecting prism transform your telescope into a telescope for nature observation. This is a great diagonal for daytime terrestrial use and night time astronomy applications for telescopes or spotting scopes.The prism is made of genuine optically processed BK7 glass, high quality optical prism inside rather than a mirror which makes your image clear and sharp. The Amici prism looks as beautiful as binoculars, but you can zoom in much higher with your eyepieces.Simply insert the erecting prism into the 1.25 "focuser and enjoy upright and right-angled images with your eyepieces - watch birds, deer at the edge of the forest, the summit cross on a mountain or a cruise ship far out on the sea. Please Note: This diagonal can only be used with refractor telescopes and some catadioptric telescopes like Schmidt-Cassegrain, Maksutov-Cassegrain, etc. Not intended for use with reflector telescopes like Newtonian / Dobsonian reflector telescopes or other variants of Newtonian telescopes.