***** **********Best Quality Guranteed. ***** 0.5 x focal reducer cuts the telescopes focal length in 0.5 to 0.8 times of original's to get a wider field of view*****Fully anti-reflection coatings on all air-glass surfaces for increased contrast*****The focal reducer is great for visual use for a bigger FOV and is indispensable when CCD imaging*****Fully metal structure design; both the ends of the interface part is 28.5 x 0.6 thread*****Directly connect the interface to the eyepiece; there is a very good performance in both visual and photography