Hi and welcome to the forum. The only thing I found out about it is you attach a camera to it shoot a 35mm slide shot. It was mentioned here
http://itc.ua/articles/olympus_flash_film_scanner_ffs-35_13820/ with a basic idea of its use. Using Google translate gives you this.
This device appeared on the market a long time and was originally designed for use with digital camera Camedia C-1400L/LX. Later on it became undeservedly forgotten, but with the release of new devices Olympus this product is sure to attract the attention of many amateur photographers.
Film Scanner FFS-35 is a metal tube, in case of which there are three optical elements in the two groups. At one end of the coupling device is holding the movable plastic panel with a screen capture and guide carriage with slides or film, on the other - a threaded hole diameter of 43 mm. To use the FFS-35, for example, with cameras Olympus Camedia C-2000 Zoom, C-2040 Zoom, C-3040 Zoom, C-4000 Zoom, C-4040 Zoom, C-5050 Zoom and similar models should purchase a special convertor ring CLA-1, providing a transition from the thread of 41 mm (on their lenses) to 43 mm. In our experiments, we used the camera C-5050 Zoom is fully automatic, and were pleasantly surprised with the results.
Naturally, the quality of reshooting significantly influenced by the temperature of light that we are sending to the screen. The developers recommend the use of diffuse daylight or fluorescent lamps. However, for example, if the screen of the device to send the window taped tracing paper, then you can successfully work with FFS-35 and in the sun.
As desired selecting lighting screen film scanner, it is easy to achieve great results digitize slides, pulling the dark areas and, conversely, obscuring the light. To retake the negatives apply special corrective filter with screw connection and sets the front of the screen. It essentially corrects color, but color saturation will increase in image editor. Although retake materials because the converter ring is usually done with the maximum focus, the image is about 80% of the frame, so the lens aperture and the dimension of the camera plays a significant role in this process.
Hope this helps and good luck with the sale.