Model SRX-MA333 PPM O2 Sensor replaces Analytical Industries Model GPR-12-333 PPM O2 sensor. Current output of this PPM O2 sensor in air is well above 600 uA thus giving a good signal to noise ratio at low PPM O2 levels. Fast response and quick recovery from air to under 10 PPM in 45 minutes. Expected sensor life at ambient temperature and pressure is 18 months. Its proprietary electrolyte formulation enhances sensor performance at extreme ends of recommended operating temperature range. Sensor is designed, developed and manufactured in the USA.