GSO's 1.25" 45-degree diagonal features an image erecting Amici glass prism that allows you to look into a telescope at a 45 degree angle. It produces an image that is oriented properly, which means that the image is upright and correct from left to right (i.e., a correct, non-inverted, non-reversed image).
This is a great diagonal for daytime terrestrial use with small telescopes or spotting scopes. It can also be used for nighttime astronomy applications, especially when you would like to match the orientation of the star field with "correct" star maps and charts.
The clear aperture is 19.5mm. The prism housing is made of high grade ABS plastic and the end barrels are made from precision machined aluminum. The 1.25" nosepiece is threaded to accept standard 1.25" astronomy filters. The diagonal comes with 2 end caps and weighs 3.8oz. Made in Taiwan.
Please Note: This diagonal can only be used with refractor telescopes and some catadioptric telescopes like Schmidt-Cassegrain, Maksutov-Cassegrain, etc. It not meant for use with Newtonian / Dobsonian reflector telescopes or other variants of Newtonian telescopes.