The air filter improves UV - C, kills bacteria and viruses, greatly helps eliminate bacteria in the air, and protects you and your family from other USB ports are enabled including the car charger, or connected by USB cable and powered by laptop, charger or wall outlet, which makes it very convenient to use in car or office/Office. (battery not included) 3 gears to choose: 1: open for about 14 hours, 2: open for 30 minutes, stop for 90 minutes (useable for about 3 days) 3: open for 10 minutes, stop for 110 minutes (use for about 7 days) use environment: 1st gear is suitable for office, living room and portable use; The second gear is suitable for the shoe cabinet and clothes: for the bathtub block 3 is suitable for the refrigerator (but the brush should be cleaned regularly to prevent it from sticking to moisture and that the ions are not evacuated) "