A 1.25-inch Moon and Skyglow filter is designed to enhance the visibility of deep-sky objects by blocking mercury vapor, sodium vapor, and other emission lines from man-made or natural sources that contribute to light pollution. This filter performs well with telescopes of all apertures and is particularly recommended for use in telescopes where conventional filters may reduce too much light. The filter fits all standard 1.25-inch eyepieces and accessories. It is threaded on both sides for stacking with other filters when needed and is housed in a durable anodized aluminum mount. Includes a protective plastic case to shield the filter from dust and moisture. Available in a 1.25-inch size, threaded to fit standard astronomical eyepieces. Specifications: Type: Moon and Skyglow filter Main Dimension: 1.25 inch Package Includes: 1 x Moon and Skyglow filter 1 x Protective plastic case