The STE-M114-040 is a 40 mm threaded extension for the 3 Stellarvue Focuser. To extend the focuser, unthread the focuser and rotator from the telescope using your hands. DO NOT UNTHREAD ANY SET SCREWS AS THESE WILL AFFECT ALIGNMENT. The extension will be threaded into the tube adapter and the focuser and rotator will thread onto this to provide 40 mm of additional distance between the objective and the focuser. Threads are M114X1.
This is one of the same extension tubes used on the SVX127D.