For the Celestron 6SE, you will need to measure the outside diameter of the flange of the stock focuser (the part of the stock focuser that mates to the rear cell, as Celestron uses 2 different size of flanges, 1 that is 1.5″/38mm and 1 that is 1.6″/40.6mm. We do have both of the size of flanges so if ordering from a distributor or direct from us, please let them know what size of flange you have.
Feather Touch® Micro Telescope Focuser for Celestron CPC-800 / NexStar 6SE/8SE SCT and SkyWatcher 150/180mm Maksutovs
If your telescope is less than a few years old, check the style of the back cell to see which version of the Feather Touch® SCT Micro Focuser you need: If your telescope has a flat back (left picture), you need the standard “C” Micro Focuser. If your telescope has a triangular pattern on the back (right picture), you will need the “CPC” version of the Micro Focuser.