William Optics Bahtinov Mask for Dew Shields - 105-148mm Diameter

This optical acrylic sheet offers 92% of light transmission that will give you the biggest and brightest diffraction spikes when focusing. This acrylic mask delivers 3 times brighter diffraction spikes than traditional metal masks.

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Diffraction Spikes: Bahtinov focusing mask

Made for telescope dew shield diameters of 105 mm to 148 mm (4.13-inches to 5.826-inches).