AST-22D oxygen sensor for diving – replacement to Model R-22S, PSR-11-39-MD, MOX-1 and MAX-12 diving oxygen sensors. This sensor fits in these rebreathers, KISS, Interspace Megalodon, Oxy Spy, Oxy2, Optima, Hollis Prism and Poseidon Rebreathers. Proprietary electrolyte formulation ensures full utilization of Pb anode, thus providing longer life without signal drift and minimizing periodic calibration requirement. Sensor is designed, developed and manufactured in the USA