The Kele GDD Series Dual Sensor Gas Detector simultaneously monitors two different gases in two different locations. The detector consists of a base unit with built-in sensor coupled with a remote sensor that can be installed up to 200 feet (6om) away. The modular design adds functionality and flexibility with pre-calibrated plug-in sensors. The GDD Series provides a 4-20 mA output in proportion to the level of gas present and two relay outputs on base unit only to activate additional horns, strobes, or ventilation systems. The unit features a two-line LCD for local indication, self test diagnostics, and a built-in 85 dBA buzzer. The remote sensor is sold seperately.The GDD Series Dual Sensor Gas Detector is designed to be used as part of a control system that helps to prevent the formation of a hazardous environment when properly installed and maintained.