The Honeywell BW Replacement Sensors are interchangeable and field-replaceable sensors. The replacement sensors are for the Micro 5 Series, GasAlert Quattro, GasAlert Extreme, GasAlert Max XT II and the GasAlert MicroClip XT or XL Monitors. Not all sensors are compatible with each of the gas monitors. Please refer to product information or contact us to be sure you are ordering the correct sensor.