Like new. Costs $88 new. Sell for $50 plus $4 for shipping.
Light Pollution Reduction (LPR) Filters are designed to selectively reduce the transmission of certain wavelengths of light, specifically those produced by artificial light. This includes mercury, and both high and low pressure sodium vapor lights. In addition, they block unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. sky glow). As a result, Celestron LPR Filters darken the background sky, making deep-sky observation and photography of nebulae, star clusters and galaxies possible from urban areas. LPR Filters are not used for lunar, planetary or terrestrial photography.
While blocking unwanted light, Celestron LPR Filters permit the transmission of more desirable wave-lengths. The wavelengths included are hydrogen alpha, hydrogen beta, doubly ionized oxygen and singly ionized nitrogen. This will improve your viewing of emission nebulae, both from urban and rural settings. Some examples of objects that will show improved contrast are: the Orion Nebula, the Rosette Nebula, the North American Nebula, the Veil Nebula and the Helix Nebula.