99% Reflectivity SV223 diagonal mirror has metal high reflective dielectric coating Surface accuracy: 1/10λ.SV182 Finderscope 15mm Eye Relief & 5mm Exit Pupil,Comfortable to Observe 15mm eye relief lets the wear-glasses astrophotography enthusiasts observe comfortably without taking off the glasses. In addition, proper eye relief effectively reduces eye fatigue for long-term observation.Double pair of magnets; SV226 photographic filters drawer compared with traditional screw rotation; magnet has stronger adsorption force; which is convenient for you to install and use.The filter is suitable for those astronomers who are already imaging using color cameras and don't want to transition to a monochrome camera set. Be the efficient astronomer with SV220 Dual Band Filters!telescope filter,SV220 telescope filter is also a fantastic solution to dealing with light pollution that is becoming more and more prevalent.The SV550 122mm telescope adopts a FPL-51 triplet apochromatic lens structure which contains one piece of ED glass. The triplet lens provides better correction of aberration and significantly reduces chromatic aberration and enhance the clarity and sharpness.