Tri-Bahtinov mask for Celestron 8" SCTs

The Tri-Bahtinov Mask is an advanced version of the Bahtinov mask that allows for even more precise adjustments and can also be used as a collimation tool This model is designed for the EdgeHD 8" SCT w/ 0.7x focal reducer.Tri-Bahtinov Focus and Collimation Mask is an ingenious new way to easily focus a telescope. Pavel Bahtinov, a Russian amateur telescope maker and astronomer, created this simple, very intuitive method and the device has universally been named after him: The Bahtinov Mask.Tri-Bahtinov Mask is based off the classic Bahtinov mask: it allows to focus a bit more objective compared to visual star focusing.The Bahtinov will produce Cross-shaped stars, with one clear line that moves along the cross as you focus. When the line is centered on the cross, you should have achieved perfect focus.   What is the Tri-Bahtinov? It essentially three Bahtinov masks in one, rotated over 120 degrees. It gives you three lines and three crosses to check collimation, along three axis simulta