No batteries needed! The fuel cell technology in the T Cell creates hydrogen in the fragrance chamber. As each molecule of hydrogen is created it forces an equal volume of fragrance out of the chamber. Natural airflow in any room distributes the fragrance throughout. Each refill lasts 60-90 days. T Cell is best placed near a door/corridor of continuous airflow as this helps the fragrance be dispersed around the room. The fragrance in each T Cell is real perfume oil, rather than fabricated fragrances which can often smell fake and ‘cheap’, the T Cell ensures a clean, fresh scent that truly lasts.