160 Bahtinov Mask -------------------------- The role of the Bahtinov mask - When placed in the front of the telescope, the telescope focusing mask can easily achieve fast and precise focusing without guessing. These focusing aids are also called Bahtinov, and the groove pattern is cut by laser. The mask can achieve precise focusing with any type of telescope, which will produce a unique, intersecting 3-line pattern. Suitable telescope diameter range for Bahtinov mask - Fits telescope tubes with an outer diameter of 158-193mm (6.22" to 7.59") Suitable for use on all types of telescope - reflectors, rafractors, Dobsonians, Mak-Cas and SCTs. Bahtinov mask application - Astrophotography application, when fast and clear focusing is required. Help astrophotographers save time and avoid blurry images caused by slight defocusing of the exposure. Just focus on the celestial object you want to shoot or nearby bright stars and adjust the focus until the intersecting 3-line pattern is displayed, indicating that precise focus has been achieved. -------------------------- Package Include: Bahtinov Mask 3 X Brass bolt