M - Men's size 8.5 and below, Women's size 10.5 and belowL - Men's size 9-11.5, Women's size 11-13XL - Men's size 12 and up, Women's size 14 and upNOTE: This product utilizes a silicone band at the top designed to keep the socks from slipping down. If your skin is sensitive to silicone, you can roll the sock top to help avoid direct skin-silicone contact and reduce the chance of any resulting skin irritation.We use “Power Bands” which are built into our socks, you will feel these bands creating tension to gently pull down the front of your foot. Then, when you bend your foot to walk, run or jump, the Power Bands become fully engaged. And finally, when you push off, the energy is returned to you, propelling you forward or upward.In addition to the added spring action, these are also compression socks which help to maintain proper blood flow and reduce swelling and discomfort. Many people wear compression socks during and after physical activity when improved circulation can ensure your muscles and joints have the necessary oxygen and nutrients they need. Est compression strength is 5-15 mmhgAvailable in knee high, black color onlyMaterial is 65% Polyamide / 25% Polyester / 10% Spandex.Patented  Learn more about VKTRY's Inside Edge Propulsion Socks