JetSox travel socks improve blood circulation, stop swollen ankles and tired aching legs associated with flying. Suitable for men and women, predominantly cotton for comfort and recommended for all travel. JetSox are 22mmHg at the ankle graduating to 16mmHg up the Calf. It is VERY important that you wear the correct size of JetSox. To determine your size, measure around your naked leg just above the ankle bone using a tape measure. Make sure you measure both left and right ankles and select your size based on your larger ankle.