The Dynavox Systems MT4 is a touch screen computer that helps people with speech, language, learning, or physical disabilities communicate.Using proprietary software, the MT4 presents a user with menus of words and pictograms to construct conversational messages. Once these messages are composed on the 6.5" touch screen, the user can have the MT4 "speak" the message for them using a state-of-the-art voice generator delivered through a high-quality 2.25" speaker. The on-screen system elements can be modified based on the user's preferences. The custom hardware has many features designed for users with physical disabilities including a rugged housing, splash-resistant sealed surfaces, an easy-to-open integrated stand, and wheelchair mount components. In addition to its core function as a voice communicator, the MT4 also has extensive IR capability that provides a user with complete environmental control unit functionality when used with common X10 devices. This means that a user can turn on lights, open doors, and talk to their family, friends, and neighbors all through a single device. Dynavox and Daedalus collaborated closely on the project, with Dynavox leading product definition, GUI programming, and electrical engineering, and Daedalus leading industrial design, mechanical engineering, and human factors. Daedalus also developed three other augmentative devices with Dynavox concurrently with the MT4: DV4, DynaWrite, and Ziba.