Optoma's 1080p ultra short throw interactive projector, the EH319USTi, is perfect for businesses, schools & colleges. It is bright & uses the generation of Touch Beam finger-touch interactive technology, enabling several people to work simultaneously on the screen without using a pen. The throw ratio of 0.25:1 means that it can project a 100" image from just 55 cm away. & having the projector installed so close to the screen avoids any shadows being cast across the screen from the presenter. It provides a complete package for engaging learning with many features, including two HDMI inputs, powered USB (Universal Serial Bus) port, powerful 16 W built-in speaker, enhanced lamp life, compact chassis & a completely mounting system for a fast & simple set-up.