Diameter/Aperture: 114mm - Focal Length: 500mm - Aluminized and overcoated mirrors -Diffraction-limited secondary mirror support -Paraboloidal (parabolic) primary mirror -Red Dot Finder for easy locating of celestial objects - 125% more light than 76mm and 165% more than 70mm refractor - Smooth rack-and-pinion 1.25" focuser - 114 primary mirror collects enough light to reveal a wealth of celestial objects. The Sky-Watcher paraboloidal (parabolic) mirror reflectors and all Dobsonian models feature a four-arm, secondary-mirror bracket with fine supports (0.5mm thick), to reduce diffraction spikes and light loss.