Paraboloid devise: The D130F650 primary mirror features a precise paraboloid shape with an aperture of 130mm and a focal length of 650mm, ensuring exceptional light gathering and image clarity for stargazing. Durable and Protective Coating: The secondary 35mm lens is coated with an aluminum film and protective layer, safeguarding it from scratches and ensuring longevity for your DIY astronomical projects. Easy Optical Calibration: Equipped with a center mark on the primary mirror, this setup simplifies the use of optical calibration eyepieces or machine collimators, making it user-friendly for both beginners and experienced astronomers. Versatile DIY Options: Choose between the primary mirror, secondary mirror, or a complete accessory set to tailor your telescope assembly according to your specific needs and preferences. Perfect for Astronomy Enthusiasts: Ideal for hobbyists looking to build their own telescopes, this accessory enhances your stargazing experience and allows for customization in your astronomical observations.