1. Universal Compatibility: Fishbone​ focusing mask is suitable for all types of telescopes, including reflector telescopes, refractor telescopes, support for Dobsonian telescopes, and support for Cassegrain telescopes, for 103mm internal diameter telescopes.
2. Accurate Focusing: This mask eliminate guesswork during focusing, overcome limitations of visual conditions, and allow you to quickly and easily achieve best focus for your telescope.
3. Secure Clamping: Focusing mask can easily clamp the telescope securely to prevent sliding, maintain proper centering, and ensure compatibility with a wider range of telescopes.
4. Diffraction Pattern: The fishbone​ focusing pattern acts as a set of artificial diffraction gratings. When light passes through the fishbone​ board, it diffracts in three different directions, forming three pairs of lines. By adjusting the focus length, the light pattern moves until the three sets of lines align, indicating the correct focus.
5. Lightweight and Strong: Telescope focus mask is made of lightweight and sturdy aluminum alloy material, the design helps maintain balance, is easy to carry, and will not damage the telescope.

Spec:
Item Type: Focusing Mask
Material: Aluminum alloy
Suitable Telescopes Internal Diameter: Approx. 103mm / 4.06in

How to Use:
Plug and play

packing list:
1 x Focusing Mask