Since it does not require a particular source of gas or water in a liquid state, the portable humidity generator is completely independent. The Humidity Generator HG-101 really has two interchangeable ink cartridges: one includes silica gel, which is used to dry a part of the air in the chamber, and the other, which has a straightforward wet sponge, that is used to saturate another portion of the air with moisture. For more details visit here: https://fensor.org/