Optomas 1080p ultra short throw interactive projector the eh319usti is perfect for businesses schools and colleges it is bright and uses the generation of touchbeam finger touch interactive technology enabling several people to work simultaneously on the screen without using a pen the throw ratio of 0251 means that it can project a 100 image from just 55 cm away and having the projector installed so close to the screen avoids any shadows being cast across the screen from the presenter