1. Universal Compatibility Suitable for all kinds of telescopes, including reflectors, refractors, Dobsonian telescopes, Mak Cas and SCT, fits telescopes with an outer diameter of 63 89mm. The focusing mask can be easily mounted on any telescope with 3 screws.
2. PRECISE FOCUSING The Bahtinov mask eliminates the guesswork of focusing and overcomes visual conditions to quickly and easily achieve optimal focusing of your telescope.
3. SECURE GRIP Three metal columns of the mask fix the telescope to prevent slipping while keeping the mask perfectly centered. The 3-pillar design allows for central alignment and compatibility with a wider range of telescopes.
4. Diffraction Patterns The focus herringbone acts as a series of artificial "truss works". When light falls through the herringbone plate, it is bent in three different directions, creating three "pairs of beams". During focus adjustments, the beam patterns shift until the three sets of rays are aligned, indicating the correct focus.
5. LIGHTWEIGHT & DURABLE ALUMINUM ALLOY The telescopic focusing mask adopts thin and sturdy design made of 1mm thick aluminum alloy material, lightweight and durable to maintain balance without damaging the telescope.

Specification:
Item type: telescopic focusing mask.
Material: Brass, Aluminum Alloy, Rubber
Weight: approx. 47 g / 1.7 ounces.

Package list:
1 x telescopic focusing mask.