The Meade 07680 Series 5000 Dielectric Mirror with Schmidt Cassegrain Adapter uses multi-layer dielectric coatings that produce 99% reflectivity for brighter, sharper images. This slip fit 2 inch diagonal with 1.25 inch adapter plus Schmidt Cassegrain thread to 2 inch accessory adapter (for LS, LT, LX90, LX200 and other Schmidt Cassegrain rear thread screw systems) is compatible with slip fit and screw mounting systems. This item does not secure the eyepieces. The optics are made of Pyrex glass and finished with dielectric coatings for maximum light transmission. This item has been tested for excellent performance interferometer. The Meade 07680 Series 5000 Dielectric Mirror with Schmidt-Cassegrain Adapter comes with a full 1 year Meade factory guarantee. Meade has everything you need to capture the night sky for experienced star shooters, serious researchers and beginners alike. Serious astronomers have flocked on Meade telescopes for years due to their high quality optical systems and patented technology. Consumers know that "Meade Optics Inside" means that what they see through our telescopes are detailed, clear and high in contrast. Look through a meadow this evening and see what you missed