●Quality Optics; SV503 Telescope’s objective lens features an S-FPL51 extra-low dispersion glass ED element; which virtually eliminates chromatic aberration ●Doublet air spaced achromatic; Quality 2-Element objective provides sharp and high-contrast images for travel and mobile use ●Fully metal construction;the dovetail base is made from black anodized solid aluminum ●Applicated to finder scope;red-dot reflex sights;green laser pointer brackets; mini guide scopes and so on ●Finder scope dovetail slots ideal for custom installation of any finder scope; fits any diameter telescope tube