The SV231 color correction filter is used to correct chromatic aberration and color unevenness. It improves the color quality and contrast of the picture by eliminating chromatic aberration and enhancing color saturation. The SV231 filter is designed with AR anti-reflection coating, ensuring image quality and brightness. Excellent optical performance and color expression add color to your deep sky photography. SV188P 1.25in nosepiece fits telescopes with 1.25in focusers. Accepts standard 1.25” eyepieces, filters, Barlow lenses and other accessories with a 1.25in insert barrel. For more comfortable overhead viewing through refractor and Cassegrain type telescopes. Correct upside down and left right reversed image. It will look like trying to read a sign in a mirror. Suitable for space viewing, for there is NO upside down or right side up in space.