These are the slippers that use medical grade LEDs to help improve circulation, relax muscles, and relieve pain. The slip-on’s 30 LEDs emit deep red (660nm) and infrared (880nm) light waves that penetrate deep into tissue to help reduce soreness common with plantar fasciitis, arthritis, neuroma, and tendonitis. AC plug. For daily 14-25 minute treatments. Sizes M (up to women’s 10) or L (up to a men’s 12).