Please note: This text was taken directly from the manufacturer.
Black shrouds are usually so funereal - but not when you're talking truss tube Dobs! For the best performance from any truss Dob, a shroud is a must. This one, custom designed for the SkyQuest XX12, is made of a stretchy nylon blend material that fits like a glove over the truss poles of the XX12, fastening with thick elastic bands on both ends. The water-resistant, opaque black fabric blocks stray light from entering the optical path, thus improving image contrast. It's also breathable, which minimizes unwanted vibration of the scope in breezy conditions. Use of the shroud will lessen the accumulation of dust and dirt on the mirrors during use, and will help prevent dew from forming on them. Made in the U.S.A.