This laser is designed to work in 2" focusers and can be used with closed and open tube designs telescopes with 1.25" focusers. Although not fully necessary, those who have closed tubes may consider the #2066 adapter with this collimator as it will extend the laser face outside of the focuser, making it MUCH easier to see and collimate your telescope. The face of the laser is visible through the cut-out on the side of the adapter. The 2062 laser and 2066 adapter may also be purchsed as a package, item #2065.
For those with an open tube or truss tube design telescope the #2062 (for 2" focusers) will be adequate.