Also known as compression stockings, these socks may stretch from the foot to the knee; some even go up to the thigh. They are generally tighter on the foot and put less pressure on areas higher up. Strong elastic presses on leg, ankle, and foot muscles and veins, creating a pressure gradient that allows blood to flow more easily back to the heart.Pressure on veins and contraction of calf muscles help move blood out of the legs. Graduated compression works best when one sits or is on their feet all day. The best results are usually seen when the socks are worn daily. For the most part, they can be removed while sleeping. Compression pressure is measured in millimeters of mercury (mmHg); this is typically between 8 and 40 mmHg (moderate compression is about 15 to 20 mmHg), while compression wear must be properly fitted based on the wearer’s ankle, calf, and thigh circumference, as well as the length of their legs.