This component is a tele-extender for SCT's which uses a Barlow Lens. It is shown below mounted in an ATS Telescope Adapter. It can also be mounted in an ATF. The Barlow lens provides a fixed magnification of 3.5x. Sells new for $100. Asking $70 or Trade
I'm also interested in trading for an "ATF" which holds the reducing lens for the Taurus Tracker III.