Farpoint Bahtinov Focus mask, FP412 - fits Celestron 11" SCT. | Fast Easy Focus for Your astrophotos a lifesaving Tool for Focusing Your Astro Camera or DSLR.: Amazon.co.uk: Electronics & Photo
Clipsable Bahtinov mask for standard diameter Dslr lens - Astrokraken.fr
Teleskop Service Bahtinov Focusing Masks - Widescreen Centre