1、Universal Compatibility: Designed to work with all types of telescopes, reflectors, refractors, for Dobsonian, for Mak‑Cas, and for SCT. It fits on astronomy telescopes with an outer diameter of 104‑146mm and can be easily attached to any telescope with the 3 bolt setup. 2、Precise Focusing: Eliminate guesswork in focusing with the telescope focusing mask. It overcomes visual conditions and facilitates fast and easy optimal focus for your telescope. 3、Secure and Centered Positioning: The 3 metal posts clamp onto the telescope, preventing slipping and keeping the mask perfectly centered. The 3 post mount allows the mask to stay centered while accommodating a wide range of telescopes. 4、Efficient Star Focusing: As light passes through the focusing mask, it diffracts in 3 different directions, creating 3 pairs of star spikes. The pattern of star spikes shifts as the telescope's focus adjusts, indicating perfect star focus when the 3 spikes align. 5、Lightweight, Resilient Design: The fishbone focusing plate is crafted using lightweight aluminum alloy and is just 1mm thick. It ensures the balance of the telescope isn't disrupted and guarantees durability and longevity. 1 x Focusing Fishbone Plate Item Type: Telescope Focusing Fishbone PlateMaterial: Brass + Aluminum Alloy + Rubber