Description: Interface Specification: M28.5 x 0.6mm thread size, suitable for 1.25 inch barrel of the telescope eyepiece. Neutral Density Filter: Reduce the amount of light without affecting color balance, neutral color will not alter the natural color of the Moon. Moon Filter: The moon filter can reduce the glares and reduce transmitted reflected light, allowing you can see the surface more clearly and study the Moon in greater comfort. Material: High quality acrylic lens and aluminum frames, increase surface durability, easy to install. Feature: Finer control of the image brightness for optimal performance. Specification: Product Size: Thread specification M28.6x0.6mm/1.13x0.02inch Interface specification: 1.25 inches (for astronomical telescope 1.25 inches eyepiece) Lens material: acrylic Frame Material: Aluminum Transmittance: ( Optional ) ND2: 52% transmittance ND4: 25% transmittance ND8: 12.5% transmittance ND16: 6.25% transmittance ND32: 3.12% transmittance ND64: 1.56% transmittance Package Includes: 1 Piece Telescope Filter (4 Pack) Note: 1. Please allow slightly error due to manual measurement. 2. Due to the difference between different monitors, the picture may not reflect the actual color of the item. 3. Wish you a wonderful online shopping!