Keep your TruSens Humidifier running at optimal levels. The enhanced water softening filter minimises mineral build up and white dust for a cleaner mist. Maintain your TruSens Humidifier by changing the filter at regular intervals. The enhanced filter softens hard water to minimise mineral build up to deliver a cleaner mist. This also helps to prolong the life of the humidifier. One filter lasts approximately 4 months for a full season of humidified air. The filter can be used with TruSens medium or large humidifiers, models N-200 and N-300. Change indicator light is displayed on your humidifier when the filter needs to be replaced.