Free Express Shipping! iOptron Photron 150mm f/9 Ritchey-Chrétien Catadioptric Telescope (OTA Only) 150mm Ritchey-Chrétien Catadioptric OTA, 1370mm Focal Length, f/9 Focal Ratio, Low Thermal-Expansion Quartz Mirrors, Dielectric Mirror Coatings, 10...