Meade Instruments 07680 Series 5000 2-Inch Enhanced Dielectric Diagonal Mirror with Schmidt-Cassegrain Adapter (Black) Multi-layered dielectric coatings that produce 99-percent reflectivity for brighter, sharper images Optics are made with Pyrex glass Dielectric coatings for the most light transmission possible Interferometer-tested for excellent performance Comes with a 1-year limited warranty