Premium Material: Made of premium acrylic, the telescope focusing mask is sturdy and , , and has a long service life. Convenient: The focusing plate overcomes the visual condition, can fast and easily provide focus for your telescopes. Suitable: The telescope plate is suitable different telescopes, such as reflector, refractor, for Dobsonians, for Mak Cas, for SCT, you just need to measure the size of telescope tubes. Lightweight: The acrylic telescope focusing mask is light in weight, will not damage the balance of telescope, and ensure it will be centered when installing. 3 Screw Sleeve: The 3 screw sleeve with anti skid silicone cover are used to fix the telescope, prevent slippage while keeping the tubes perfectly centered.