Material: nylon+spandex+rubber latex thread. Size: S, M, L, XL. Weight: 120g approx. Type: Self-heating knee pads. Functions: protect the knee, prevent arthritis and relieve joint pain. Package: knee sleeve *1 pair. The pads can protect your knees, prevent arthritis and relieve joint pain. They feature magnetic therapy to improve blood circulation and help relax muscles and reduce fatigue. The high-elastic fabric is skin-friendly, breathable, stretchable, soft and comfortable to wear. The tourmaline heat-sensitive material contacts with human skin, and body movement releases energy and makes the knee feel hot. Three sizes are available to ensure a comfortable fit to your knee, suitable for the entire family and different body needs.