The Explore Scientific AR127 Air-Spaced Doublet is a classic crown-and-flint achromatic refractor designed to deliver superior optical performance in a compact, fast f/6.5 focal ratio. This 127mm (5-inch) aperture telescope reveals stunning, sharp images at a fraction of the cost of comparable apochromatic refractors. Built to endure the demands of public star parties and educational outreach, the AR127 features heavy-duty, professional-grade components including a smooth 2" dual-speed focuser, a one-piece 2" diagonal with 99% dielectric coatings, and the Explore Scientific Hybrid Finder Scope Base with an 8x50 non-illuminated straight-through finderscope and quick-release bracket. The sturdy cradle ring assembly with Vixen-style dovetail allows easy mounting on your choice of alt-azimuth or equatorial mount. Add your preferred eyepieces and start exploring the cosmos. Interferometric optical data is available upon request after 120 days of ownership — contact Customer Service for details.