Feature:1. Having obvious effect to eliminate harmful city light.2. 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.3. Using international standard discusion thread, 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.4. Made of good quality aluminum alloy, solid, durable and wear-resistant and corrosion-resistant.5. Compact size, lightweight and portable.Specification:Item Type: Astronomical Telescope FilterMaterial: Aluminum AlloyColor: BlackSize: Approx. 31.7mm/ 1.25 InchWeight: Approx. 27 gApplication: Universal for astronomical telescopePackage List:1 x Astronomical Telescope Filter