This deodorizer is a non-toxic, hypo-allergenic and flame resistant unit that smells as if the real plant was in the room. Each fragrance cartridge (made from natural plant based oils) lasts 3 months depending on room and dispenser size. Each unit has an on-off switch and an adjustable fragrance output control. Tan Color unit runs for 3 months on one Alkaline D-cell battery. The Supra unit has a light-activated auto shut-off system. Double stick foam tape is supplied for easy installation. Units do not come with odor cartridges, you must order these separately. Cartridge choices are: Apple, Crusair (orange), Lemon, Grapefruit, Hibiscus, Jasmine, Orchard Peach, Rain Forest, Sun Green, or Tropic Delite.