When it comes to keeping the optics of their telescope clean, Astronomers can be justifiably meticulous. Dust is everywhere, and the accumulation of it on the primary and secondary mirrors brings down overall image quality. And although some optical dust collection is unavoidable, it is possible to keep dust from reaching your optics between observing sessions. Proudly made in the USA, the AstroZap dust cover material is made up of a cotton and nylon mixture. An elastic strap is stitched into this dust cover, allowing it to fit comfortably over the open end of Dobsonian telescopes. This keeps your Dobsonian's optics from accumulating an excessive amount of dust for clearer images.