Polartec 300 Ear Covers Cycling Ear Warmers Polartec Ear-Covers Keep Your Ears Warm and Reduce Wind Noise. Made From Authentic Polartec 300 Feece and Velcro Brand Fasteners. Acoustically Transparent - Not Sound Blocking (they are safe for road cycling). Road and Wind Tunnel Tested. Proven Warmth Effectiveness (all cycling speeds). Recommended by Adventure Cycling Association, Bicycling and Outside Magazines.