The Otis Instruments OI-6900 Series Ambient Air Toxic Gas Detector is a versatile assembly that uses an electrochemical, low-powered infrared, or PID sensor element to detect a variety of gases.WireFree, dual battery powered available with GEN II 900 MHz or 2.4 GHz Radios. Magnetic switches allow for non-intrusive calibration while in the field as well as full system setting and diagnostics.