The S4000TH Intelligent Gas Sensor is a microprocessor-based transmitter designed for use with General Monitors’ thin film metal oxide semiconductor (TFMOS) sensors to detect H2S gas. The unit features one person calibration and can virtually self-calibrate by simply activating a magnetic switch and applying gas. It detects hydrogen sulfide in 0-20 ppm, 0-50 ppm or 0-100 parts per million (ppm) levels over a wide temperature range.