BONECO AOS A200 Hydro Cell A200 Humidifier Filter with Activated Carbon, 2 pack Uses activated carbon technology to provide constant freshness in BONECO ultrasonic humidifiers Direction: Rinse and place the Hydro Cell in the tank of your unit Activates as soon as it comes into contact with water even if the humidifier is switched off To ensure the highest water quality in your humidifier, exchange the Hydro Cell every 1 to 2 months, depending on the water quality Uses: All BONECO & AIR-O-SWISS ultrasonic humidifiers except the 7146 Travel