AST-75D-PO2 Oxygen Sensor, a galvanic type micro fuel cell replaces AII Model AII-11-75-PO2 and AII-11-75-PO2-D used in Palm O2 analyzer. AST-75D-PO2 oxygen sensor is mounted internally. For external sensor, use AST-75D-PO2R, Its innovative design with proprietary Pb anode structure provides with excellent stability and ensures full utilization of the anode without signal drift thus minimizing frequent frequent calibration. AST brand sensors are designed, developed and manufactured in the USA.