flip mirror box with reticle eyepiece used to center guide star for autoguider chip. Eyepiece has reticle to match ST4 field of view. You can place an illumination source into the reticle hole to illuminate the crosshairs. Illumination source not included. Unit attaches directly to ST4 unit. Then place the ST4/flipmate into your guidescope and acquire guidestar, center, and you should have the guidestar on the ST4 chip. You may have to do an initial calibration of the unit with the ST4. I last used in Feb. 2002 and the unit was centering the guidestar just fine. Flip mirror also serves as a convenient way to take dark frames without removing ST4 or covering guidescope optics. Unit was manufactured for Pocono Mountain retailers. Bought in Feb. 2001. New was over $200. Motivated seller.
Asking $130 plus shipping