The FR237 Focal Reducer and eFinder Assembly is actually two accessories. It is a variable focal reducer that will reduce an F/10 optical system to F/3.75 and it is an ultra compact wide field telescope that may be used for imaging, an electronic finder or autoguiding. The image at right shows the three parts that make up the entire assembly: an achromatic focal reducer lens (left), a 4 inch "eFinder" extension tube (middle) and a short 1.25" extension tube (right).
It is in excellent condition. May be used with the STV; ST-237; ST-237A; ST-5C and Pixcel 255. $165 shipped CONUS.