Flight Compression Socks Cotton have compression levels from 15 to 21mmHg. Perfect for everyday use, these flight socks increase blood flow in the legs, reduce the feeling of heavy legs, swelling and pain and help prevent the risk of DVT (Deep Vein Thrombosis - known as Economy Class Syndrome in long distance flights). Knitted in 100% natural cotton using the latest double cylinder technology, these graduated Class I compression socks (15 to 21mmHg), for Men and Women, are breathable and their benefits clinically proven. For the comfort of flight attendants and anyone who spends long periods of time on their feet, they are indispensable Skypro Sky Compression socks are manufactured to the highest quality in accordance with British Standards