Fashioned with controlled compression, which assists the muscles in pushing the venous blood up the legs back toward the heart. Improved circulation thus reduces leg fatigue. In addition, QCS Men's Medical Socks meet the needs of the active man. Firm compression 20-30 mmHg. Medium fits shoe size 7-1/2 - 10, ankle 8-3/4 inch - 10 inch, calf circumference 12 inch - 16-1/2 inch.