Astronomical Telescope Filter Have obvious effect to eliminate harmful city light. Using nanometer coating system to ensure that the film layer high temperature resistant, corrosion resistant, not easy to fall off and other characteristics of uniform coating. Using international standard discusion thread, it's suitable for a variety of astronomical telescope with British thread standard. Align the filter thread to the rear thread of the eyepiece, rotate the filter lens into the eyepiece, and then watch and use it. Astronomical Telescope Filter is Made of good quality aluminum alloy, solid, and wear-resistant and corrosion-resistant. Astronomical Telescope Filter has Compact size, lightweight and portable.