SRZ-MT12 PPM oxygen sensor is compatible with Teledyne Class A-2C, Analytical Industries XLT-12-123, AMI T-4 and Panametrics OX-2 PPM oxygen sensors. Its proprietary electrolyte formulation offers excellent compatibility with sample gas containing acid gases such as CO2, traces levels of H2S and SO2. All AST sensors are gas tested for stability, accuracy and recovery from air to low PPM levels. All PPM O2 sensors are sealed in metalized polyethylene bags under nitrogen. AST brand sensors are designed, developed and manufactured in the USA.