Sky-Watcher Evostar-100ED DS PRO 100mm (4"") f/900 Fluorite Apochromatic Refractor Optical Tube Assembly. The Sky-Watcher Evostar ED DS-PRO series is the name for the new generation of professional quality telescopes and mounts of the Sky-Watcher range, targeted at the most discerning and critical observers. Each telescope is manufactured to extremely high levels of optical and mechanical precision, undergoing very strict quality control procedures to ensure the highest standards of quality and performance are consistently maintained. Each objective lens is finished by hand by skilled technicians and the quality of each telescope is monitored by means of a Ronchi test and artificial star test. No effort is spared to reach optimal optical quality.Please note, this is an Optical Tube Assembly only, mount and tripod are available separately.