SVBONY 1.25 31.7mm 0.5X Focal Reducer Thread M28x0.6 for Astronomy Telescope Eyepiece Astronomy (Black) The 0.5x focal length reducer effectively halves the focal length of the telescope to achieve lower magnification, wider field of view and shorter exposure time for astrophotography Features: 1.100% brand new 2.Fits all standard 1.25 scope eyepieces 3.Its role is to shorten the focal length, increasing the field of view, usually for a longer focal length telescope 4.The reducer has standard 1.25inch telescope threads M28.5x0.6 and fits onto the nose of any 1.25 inch eyepiece, diagonal, extender tube, or camera adaptor fitting that format 5.Reduces your telescopes focal ratio by 0.5 6.Increases imaging area 7.Optical lens helps transmit more light 8.Can both have a filter attached and be threaded onto an eyepiece or camera 9.Nice anodized aluminum housing 10.It is not recommended for very fast scopes or very wide angle eyepieces for visual Specification: 1.Focal Reducer: 0.5X 2.Lens Material: pure optical glass lens 3.Lens material: Broadband coating 4.Sleeve material: Metal 5.Barrel Size: 1.25 inch / 31.7mm 6.Thread interface: M28.5x0.6 pitch (Fine Thread) 7.Total item length (including external thread): 0.55inch / 14mm 8.Total item length (excluding external thread): 0.43inch / 11mm 9.Clear aperture: 0.87inch / 22mm 10.Weight: 0.42oz / 12g 11.Color: Black How to use it?