The testo 340 is built to measure high concentration with its unique, automatic 5X dilution system. When the concentration set-point is reached, precise amounts of dilution air are added thereby lowering the concentration applied to the sensor. The analyzer automatically computes and displays the correct values. Simply install the sensors in the dilution slot for a range 5 times greater. It’s that simple. If you need more flexibility select “dilution overall” to extend the range of all sensors by a factor of 2. The dilution system, combined with replaceable filters will maximize your tuning capabilities and reduce the cost of ownership.