SVBONY 1.25 moon and skylow is a multi-band pass filter transmitting a high percentage of light in the visual spectrum; the filter enhances contrast when observing brighter objects including the moon and planets It also will suppress sky glow from artificial lighting and background glow reflected when the moon is up Mild effect of darkening background of the night sky: So that the fainter objects is more clearly seen contrasted against the blackness of space Effectively filters out stray light: Filtering Selective wavelengths of low-pressure sodium and other man-made sources typically used in street lighting It enhances the views of deep-sky objects by increasing the contrast of these objects against the background sky While nebula filters transmit only a few select wavelengths corresponding to various atomic lines The filter transmits a large portion of the continuous spectrum while blocking a few select lines of the more common man-made light Neodymium provides a unique;selective;blocking feature in that this element greatly reduces glare without reducing important color and brightness variations Features: 1.25 skyglow and moon filter for telescope eyepiece cutting light pollution Effectively filters out selective wavelengths of low-pressure sodium and other man-made sources Premium quality metal rim;thread and blue glass lens Fits all standard sized 1.25 eyepieces and accessories Usage:the filter thread after thread eyepieces;rotate the filter into the eyepiece Specification: Lens material: pure optical glass lens Sleeve material: metal Caliber: 1.25/31.7mm Total item length (including external thread): 0.39/ 10mm Total item length (excluding external thread): 0.28/ 7mm Clear aperture: 0.94/ 24mm Filter thread: M28.5x0.6 Package include: 1 x SVBONY moon and sky glow filter - 1.25 moon and skyglow filter is a multi band pass filter transmitting a high percentage of light in the visual spectrum;the filter enhances contrast when observing brighter objects including the moon and planets - Telescope eyepiece cutting light pollution;the filter has a mild effect of darkening the background of the night sky so that the fainter objects are more clearly seen contrasted against the blackness of space - The filter effectively filters out selective wavelengths of low pressure sodium and other man made sources typically used in street lighting;although it is not a nebula filter;it enhances the views of deep sky objects by increasing the contrast of these objects against the background sky - Premium quality metal rim and thread with blue glass lens;the filter will fit all standard sized 1.25 eyepieces and accessories;it is mounted in a nicely anodized housing - Standard filter thread for any 1.25 telescope eyepiece and other accessory;comes with a plastic box to keep it safe and clean when not in use;Its a great birthday christmas gift