By softening the water quality used to produce mist, this demineralization cartridge maintains an ideal pH balance that is better for the skin while reducing the presence of PM 2.5 particles, which helps protect your respiratory tract. Avoid the formation of white dust inside the humidifier and around your furniture thanks to the ionic demineralization process. White dust buildup often reduces performance and leads to early malfunctions in humidifiers, using a high-efficiency cartridge helps minimize these risks. for DREO HM311/311S, HM524/524S, HM306 Color: As shown in the picture Material: Plastic Package Contents: 3 x humidifier filter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.