This Cigar Oasis XL Plus is an electronic humidifier that is fully automatic. While it is the same size as the Cigar Oasis XL, the basic difference is in the change of airflow and water cartridge to allow the unit to pick up more moisture and provide more rapid humidificiation for larger humidors, chests and end table humidors. It comes standard with a large water cartridge, which uses foam to estimate wicking and water splashing around. The manufacturers recommend that this unit be used with the AC Power adapter since it will run more frequently in larger humidors. However, an optional battery pack/water cartridge unit can be attached to the control unit for battery-powered operation. Cigar Oasis XL Plus is designed to keep your cigars fresh.