Features: 1.100% brand new 2. Suitable for all standard 1.25 "eyepieces 3. Its function is to shorten the focal length and increase the field of view, usually used for telescopes with longer focal lengths 4. The variable diameter mirror has a standard 1.25inch telescope thread M28.5x0.6 and can be installed on the nose of any 1.25inch eyepiece, diagonal, magnifying tube, or camera adapter accessory 5. Reduce the focal ratio of the telescope by 0.5 6. Increase the imaging area 7. Optical lenses help transmit more light 8. Filters can be installed simultaneously and screwed onto the eyepiece or camera 9. Exquisite anodized aluminum shell 10. Not recommended for very fast telescopes or very wide angle eyepieces Specifications: 1. Brand: SVBONY 2. Focusing agent: 0.5X 3. Lens material: Pure optical glass lens 4. Lens material: broadband coating 5. Sleeve material: metal 6. Gun barrel size: 1.25 inches/31.7 millimeters 7. Threaded interface: M28x0.6 pitch (fine thread) 8. Total item length (including external threads): 0.55 inches/14 millimeters 9. Total item length (excluding external threads): 0.43 inches/11mm 10. Transparent aperture: 0.87 inches/22mm 11. Weight: 0.42 ounces/12 grams 12. Color: Black The package includes: 1X SVBONY 1.25inch 0.5X defocusing mirror