Graduate designer Dorothee Clasen has invented a wearable device called Tong that is worn in the mouth to operate a computer using the tongue. Designed for her master's degree at Köln International School of Design, Tong is made from a custom dental retainer fitted with a ball with a magnet on a set of rails on the underside. A wire connects from the brace to a Wi-Fi transmitter that hooks behind the ear. The wearable device enables the user to interact with a computer by using their tongue to move the ball backwards and forwards. Clasen also built a computer game to play with the device. Also called Tong – a twist on 1970s Atari arcade game Pong – the user can bat a virtual ball back and forth against a digital opponent. Tong would be useful for people with certain disabilities, suggested Clasen, or for people whose work keeps both hands occupied at the same time.