The Explore Scientific Neutral Density Filter transmits light uniformly across the entire visual spectrum. It serves as an excellent filter to reduce glare and irradiation when observing the Moon with any telescope 4"(10.2cm) and larger.
The Explore ND Filter has a density of 0.9 and a transmission of 13%. Besides working great on the Moon, it will help split close double stars where one star is much brighter than the other. Neutral density filters also help decrease brightness when using your telescope for terrestrial viewing on a bright, sunny day.
Limited Warranty is one year, which converts to the Explore STAR Transferable Extended Life of the Product Warranty when product is registered on explorescientific.com within 60 days of purchase.