Features:-There are two gears (high/low) in total, which can be adjusted as needed to achieve the best effect.-Built-in rechargeable battery, can be used for 30-60 hours after charging.-The use of electrolysis to generate negative ions can form a microscopic health barrier that can effectively fight against air pollutants such as pollen, dust, and secondhand smoke.-It adopts a small and compact design and can be worn around the neck, making it convenient to use in complex places such as cars, offices, subways, airplanes, bedrooms, etc.-It is very suitable for children, students, the elderly and other groups to better protect their health.Specification:Color: whiteMaterial: ABS+PCBattery capacity: 700mAhWorking time: low gear-60h, high gear-30hSilent effect: .