A dew cap reduces the formation of dew, prolonging your observing sessions. Orion's revolutionary Flexishield dew cap is the answer. It is made of durable, flexible ABS plastic that won't chip of break. It wraps snugly around your telescope tube and fastens with an easy velcro strip. Once in place it is very rigid and won't block the optical path. Best of all it can be stored flat or rolled up tight for convenient storage and transport. It can be used in conjunction with a heater such as the Orion DC Dew Zapper. It also makes an excellent lens shade when using your telescope in daylight. Fits 11 inches SCT telescopes.