Amazon.com : Astromania Bahtinov Mask Focusing Mask for Telescopes - FM200mm for a Tube Outer Diameter (OD) from 215mm-260mm - can be Mounted with The Brass Screws Inside or Outside The drawtube :
A beginner's guide to Bahtinov masks | BBC Sky at Night Magazine
Which is the best alternative to the Bahtinov Mask - Carey or Tri? - YouTube
Farpoint Adjustable Tri-Bahtinov Focus Mask - 2.5 Inch to 4.5 Inch OTA – FarpointAstro
Amazon.com : Astromania Bahtinov Mask Focusing Mask for Telescopes - FM60mm for a Tube Outer Diameter (OD) from 65mm-100mm - can be Mounted with The Brass Screws Inside or Outside The drawtube :
Moving towards better focusing: testing the Bahtinov mask – Epistulae Astronomicae
Better alternative to Bahtinov Focusing Mask - ATM, Optics and DIY Forum - Cloudy Nights
Farpoint Snap-In 77mm Camera Filter Bahtinov Focus Mask FP443
Farpoint Bahtinov Focus Mask for Celestron 6" SCT # FP409
Comparison of Spike Images from Bahtinov and Tri-Bahtinov Masks and DIY: Bahtinov Masks. - YouTube