Improves circulation to help minimize swelling. Relieves tired, achy legs. Great for travel and for being on your feet all day. Designed with graduated compression. Compression decreases gradually up the leg with maximum compression at the ankle to help promote healthy legs. Helps relieve symptoms of mild varicose veins. Helps prevent deep vein thrombosis (DVT). Durable, reinforced toe and heel. Comfort band ensure socks stay neat and in place. Compression level: 20-30 mmHg. Extra large fits US shoe size 12-1/2 and over. From floor to bend in knee: Calf measurement. 17": 18"-19"; 18": 17"-19"; 19":16"-19".