Solomark Bahtinov Focus Mask for Telescopes 80mm-suitable for 80mm Diameter Telescope Bahtinov focus mask for telescope 80mm Masks now feature 3 holes which can be attached with 3 screws to prevent the mask from falling all the way to the ground It will take less than 1 minute to achieve perfect focus with your new mask and will mean you spend more time imaging photons rather than focusing them Light weight so you wont upset the balance on your scope.