The hanging-neck type is convenient to carry around. Small in size, it can purify the breathing air at any time. Purifies odors and impurities from the surrounding air. Great gift for friends, kids and family, suitable for any group of people. No need to replace any cartridge, save you excess consumption. 20+ million negative ions air purification principle: negative ions gather, impurities precipitation; anion decompose peculiar smell, particles . Adsorb PM2.5 particles to degrade. Negative ion air purifier, no sharp angle, no radiation . For children, the elderly and pregnant women, 0 radiation is suitable for them to enjoy a fresh and comfortable life. Quiet operation, sleep peacefully. Hanging- neck air purifier, negative ion purifier, 700mAh capacity battery, charging for 30 minutes, continuous use for 15 hours. The USB interface is more convenient, and the switch is integrated with one button. Negative ions are released through the fiber brush, there are two types of regulation, intermittent release and continuous release, the negative ion content in the forest is high, so you will feel that the air there is good, the principle is the same