1. Wide Applications: Works with all types of telescopes, mirrors, refractors, for Dobsonians, for Mak Cas and for , all you need to do is measure your telescope tube size and choose the appropriate mask size.
2. Good Functions: The mask takes the guesswork out of focusing and even overcomes conditions to give your telescope the best focus quickly and easily.
3. Metal Posts: The mask grips the telescope tube gently and firmly with three metal posts. These metal posts come with scratch resistant silicone covers to your telescope . This prevents slippage while keeping the mask perfectly centered.
4. Post Installation and Lightweight Design: Thanks to this 3 post mount, the mask remains centered while fitting a wider range of telescopes. The bahtinov focus mask for telescopes is lightweight so you won't upset the balance of the scope.
5. Applicable Size: The outer diameter of the bahtinov mask supports the telescope objective lens in the range of 120 to 160mm (there is a 1?2mm error in manual measurement).

Specification:
Item Type: Telescope Focus Mask
Material: Acrylic
Thickness: Approx. 2mm / 0.08in
Color: As Pictures Shown
Weight: Approx. 46g / 1.6oz
The Outer Diameter Size Range of the Telescope Objective Lens Is Supported: Approx. 120-160mm / 4.7-6.3in (there is an error of 1-2mm in manual measurement)

packing list:
1 x Bahtinov Mask
3 x Mounting Accessories