BENESU New Arch Life Socks: Taping effect supports lateral arch formation. Reduces foot strain and fatigue. Recommended for people who suffer from foot pain, swelling, and other problems. Size Reference: Size S: 7.1 - 8.3 inches (18 - 21 cm); Size S: 8.9 - 9.5 inches (21 - 23 cm); Size M: 9.4 - 10.6 inches (22.5 - 24.5 cm); Size standards have been changed. You can see mistakes as soon as you put them on. Magic socks! Try it!