Helps reduce white dust, which is a byproduct of minerals caused by hard water. Crane humidifier filters also feature antimicrobial material to help reduce mold and bacteria growth. For best results, replace filter after every 30-40 filling or every 1-2 months under normal use, or when the humidifier has not been operated for an extended period of time. To install, simply replace tank cap with filter and insert into full-water tank. Fits most Crane humidifier styles including Adorables, Drops and Droplets.