doubles the horizontal frequency of all 15 kHz screen modes to 31.5 kHz - other screen modes are passed through
removes flicker of interlaced screens
connects externally to the 23 pin RGB port
being an external unit, it has to encode the RGB signal, flicker fix, split to RGB and sync again - this reduces the quality of the video signal
sync delay adjustment potentiometer
claimed to be compatible with the Video Toaster and all genlocks, but it's not in many cases - the genlocked video signal is passed through without scandoubling
scandoubled screens are much draker than passthroughed screens
high power consumption - the screen may go darker when the floppy drive is accessed