Sky watcher skymax 150 pro 150mm 6 f1800 maksutov cassegrain optical tube assembly black diamond 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 available in apertures of 150mm and 180mmskymax black diamond pro series maksutov cassegrains are manufactured to extremely high levels of optical and mechanical precision undergoing very strict quality control procedures