Celestron radial guider. No longer have the SCT. This unit is hardly used. Should work on any SCT with threads the same as Celestron or Meade. No reticle included. The following description is shamelessly borrowed from the Celestron website.
Specifically for use in prime focus, deep-sky imaging or astrophotography with Schmidt-Cassegrain telescopes, the Radial Guider is compact and sleek in design. This accessory makes it possible to simultaneously photograph and guide through the optical tube assembly of your telescope. The Radial Guider also eliminates the problem of differential flexure, because you’re both guiding and photographing through the telescope.
The Radial Guider is compatible with Celestron’s C5, C8, C9¼, C11 and C14 telescopes and comes with a unique prism angle adjustment screw. It must be used with a guiding eyepiece, camera T-Ring and drive corrector (dual axis preferred). Primarily for use with catadioptric telescopes, but also works on refractor telescopes having adequate back focus.
This guider is a tremendous improvement over conventional off-axis guilders. Not only is the angle of the prism tunable, but it also maintains a fixed rigid camera orientation while still offering users the freedom to move the guiding eyepiece radially about 135°.