Buy as a set and save 5%.MB-MO-SE1:Monitoring the atmosphere of MBRAUN systems for residual moistureMeasuring range: 0-500ppmPlease note that the sensor head must be coated regularly with 85% phosphoric acid.MB-OX-SE1:Monitoring the atmosphere of MBRAUN systems for residual oxygen contentMeasuring range: 0-1000ppm(Original item number: 1500685, 1500686)