[Jethro777 (Jethro)]

I have a 10" GSO Dob, and want to make sure it is fine-tuned.
What exactly do I need? The manufacturers don't exactly make it easy. The GSO one has a 2" focuser, and I have a 1.25" adaptor of course.

I understand there is the catseye American version, and the Astrosystems one.