Features: Moon filter installation size is 1.25 ". Both sides have a universal 1.25 "threaded interfaces, which can be connectedto any 1.25 " telescope eyepiece and other telescope adapters. The moon filter optical glasses only transmitted 13% of the incident light, which enhances the contrast and can distinguish the details on moon, which is very suitable for small telescopes. It can prevent the glares of the moon and reduce the brightness of the lights, so that we cansee morelunar features, such as gullies, mountain and valleys. Not only does it help you see moresurface features and details, but the moon filter can be used in combination with other filters, so you can learn them more comfortably. When the moon is in the fullmoons, it will produce dazzlings light. It is recommended that you use the moon filter to achieve the best viewing quality. Specifications: Material:Aluminum+Optical Glass Size:Approx.31.7mm/1.25inch Lens material: optical glass Frame size: 1.25 inches (about 31.7mm) Frame material: metal-aluminum Thread specification: internal and externalM28.6x0.6mm Net weight: 8g Gross weight: 18g 1.25 inch moon filter aluminum frame light pollution filter for telescope eyepieces optical glass reduces moon brightness, enhances contrast and ability to discerns moonsurface details. Easy to install, both sides are universal 1.25 "threaded interfaces, can be connectedwith any 1.25" telescope eyepiece. Aluminum alloy frame and optical glass. Durable, rust-proofsurface, can be used for a long time. Package Includes: 1x Moon Filter note: ①.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. ②.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks for your understandings.