The Svbony 1.25"/2" polarizing filter is a premium anodized aluminum. Optical glass polarizing filter designed to reduce the amount of light entering the eyepiece and increase contrast and reduce glare for more detail . 

It allows maximum contrast of lunar detail and enhances the contrast of the moon and planets in photographic images.

It progressively dims the view, increasing the contrast for telescope eyepiece.  This eyepiece is for visual use.