Description: A. 1.25 inch Moon and Skyglow filter is designed to improve the visibility of deep for sky objects by blocking out the for mercury for vapor, sodium for vapor, and other such emission lines from man-made or natural sources which contribute to moon filter. B. Works well in telescopes of all apertures but is highly recommended for use on telescopes, where conventional filters swallow up too much light. C. The filter will fit all standard sized 1.25 inch eyepieces and accessories. Can be threaded on both sides for stacking with other filters if necessary. It is mounted in a nicely anodized housing. D. Comes with sturdy plastic case-proect the eyepiece from dust and moisture. And it is available in two sizes, threaded to fit standard 1.25 inch astronomical eyepieces. Specifications: Type: Moon and Skyglow filter Main Dimension :1.25 inch Package Include: 1 X Moon and Skyglow filter 1 X Sturdy plastic for case