SV128 Variable polarizing filter Suitable for 2 inch Telescope Eyepieces, reducing the amount of light entering the eyepiece increases the contrast between the moon and the star, allowing you to see more details about the moon and the stars. Does a good job of cutting out light pollution. The sky is much more black than without it. However it does cause a halo. If you turn down the exposure it does go away or weakens up enough not to notice. Gain new enlightenment into the night sky by making your darks darker and your blacks blacker. This filter is a necessary component of any well stocked filter collection.