Halo Headbands are technically designed to keep sweat and sunscreen 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). The high performance DriLine material of the headband quickly evaporates moisture so you stay dry 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. Works great under helmets of all kinds. One size fits most.