Our most favorite diffuser. This professional model nebulizing diffuser has a variable speed pump that controls output for areas up to 1500 sq’ or down to 100 sq’. Built-in 3 way switch controls Intermittent, Continuous or Off operation. Intermittent cycle runs pump at the speed you’ve set for 5 minutes, turns the motor off for 25 minutes, then repeats the cycle. Cuts oil usage 80%, eliminates OFS (olfactory fatigue syndrome). The only drawback we could find was the unit makes some noise when on higher settings.