Halo Headbands are technically designed to keep sweat out of your eyes and off your glasses while training, working out, racing, or just working hard. Every Halo Headband includes the soft and comfortable Sweat Block Technology. This exclusive water-tight seal redirects sweat away from your face. (US Patent 6,567,991). 2 layers high performance DriLine material keeps your ears warm and comfortable. It is lightweight, durable, and abrasion resistant which will not lose shape.The microfiber polyester that has been embedded with SILVER IONS. These silver ions prevent the growth of bactreria - No bacteria - No smell. Shaped design is narrow at the forehead for comfort yet wider by the ears for warmth and coverage. Works great under helmets of all kinds. One size fits most.