Used Manual Projector American Optical Double Tube This American made projector is designed to provide performance and dependability. Testing distance is 6 to 20 feet (under 10’ with an optional auxiliary lens), and coated optics provide a bright, crisp image on the screen. Unique air-flow design protects against burns and prolongs bulb life. There is a horizontal/vertical selector, and finger-tip controls that may be operated from either side.