The Proximity Sensor, model PRX-104, is a sensor switch designed for use by individuals with severe physical or upper extremity disabilities or spinal cord injury. This adjustable single-function switch requires no touch or pressure. This proximity switch can detect something that has an electronic capacitance, such as a hand or finger up to one-quarter inch away. This sensor ignores non-capacitive materials and is mountable on a headrest or tray. When used with a sensor output and a power supply, this sensor gives the user switch access to a number of components using a 1/8 mono jack. POWER: Requires 12 or 24 volts direct current (DC). OPTIONS: Power 100, Power 5, or Sensor Output. DIMENSIONS: 1 3/8 inches wide x 2 3/8 inches long x 9/16 inch tall.