Smart Knee Massager - Knee Protector Pain ReliefThis product is designed in accordance with ergonomics and physical massage techniques, through air pressure massage, vibrating ball massage, intelligent control of constant temperature hot compress, and combined with visible red light with a wavelength of 600 700nm, it can better promote blood circulation and relieve joint discomfort. Specification : Name : Knee Massager Applicable people: Suitable for people with knee discomfort. Charging time: 3 4