GSO Mirror Set for Self-Construction of a 16" f/8 RC Telescope The mirror set consists of a hyperbolic primary mirror and a hyperbolic secondary mirror for the construction of a Ritchey-Chretien telescope. ♦ With the mirror set you can build an RC telescope with 406 mm aperture and 3248 mm focal length. ♦ The set consists of primary mirror and secondary mirror without mechanical accessories ♦ The mirrors are made of quartz glass (similar to Zerodur) for stable focus position. ♦ 99% reflectivity on main and secondary mirrors with a quartz protective layer