Astronomers can be understandably finicky about keeping their telescope optics clean. This is because dust is everywhere. But while it's close to impossible to completely prevent it from gathering on the primary and secondary mirrors, you can avoid dust accumulation between observing sessions with this dust cover from Astrozap. Proudly made in the USA, AstroZap's dust cover material comes from a blend of nylon and cotton. An elastic strap is sewn in, enabling a comfortable fit over the open end of Truss-Tube RC Dobsonians. This results in clearer images as optical dust is kept at bay.