BONECO Demineralization Granule Refills, 1 Box Easy replacement of the granules of demineralization cartridge 7531 For water mist without minerals or limescale 3 Packs of Granules per Box - Enough for 3 granules changes Replace granules every 2  3 months, or more frequently in areas with hard water Use: for all BONECO ultrasonic humidifiers except from U7146 Travel Enough for 3 granules changes" to "3 Packs of Granules per Box - Enough for 3 granules changes