Product details:

The Cordless Knee Heat Therapy Wrap uses Far Infrared Ray (FIR) heat that penetrates up to 3" of bone and muscle to melt away chronic pain. The best part is it doesn't get "red hot" to the touch so it's safe for those with sensitive skin. Experience up to five hours of soothing heat on a full charge. Helps ease pain from arthritis, tendinitis, runner's knee and other conditions. Features four heat settings (up to 140°F), plus soft, stretchy fleece material, Velcro straps and automatic safety shutoff. Available in two sizes: S/M (knee size 12"-18") and L/XL (knee size 18"-23").