The Animal Humidifier Water Filter by Crane is an optional filter cartridge for the Frog, Panda, Elephant, Penguin, Pig, Cow and Dragon Cool Mist Humidifiers by Crane. This filter reduces "white dust", bacteria and mold spore build up, and installs easily into all of the animal Cool Mist Humidifiers. By using this water filter in your Crane humidifiers, you're unit will be able to supply your home with the cleanest, coolest air possible.