SRX-MA100-M PPM Oxygen Sensor is designed for applications where sensor can be exposed to air frequently during use. The lower limit of analysis is 0-100 PPM but quickly recovers from air to low PPM levels. SRX-MA100-M is a drop in replacement to AII Model GPR-12-100-M O2 sensor. Its innovative design with electro-etched sensing cathode provides with extremely smooth sensing surface for excellent signal stability, very low noise and drift. This sensor, with its proprietary electrolyte formulation, enhances sensor performance at extreme ends of recommended operating temperature range. Sensor is designed, developed and manufactured in the USA.