Additional device for the Freedom computer for nitrox analysis (the measuring of oxygen concentration in the breathing mixture). You only need to connect it to a connector of the Freedom computer of any software version and you can measure. The analyzer is supplied WITHOUT an oxygen sensor. Use Divesoft R22S oxygen sensor with Molex 3-pin connector (or equivalent). Oxygen sensors previously used in rebreather (type R22-D) can also be used in the probe, if they are still able to measure full range of oxygen pressures in atmospheric pressure safely.