Achilles tendon support: new premium version includes heat sealed EVA foam pad shaped to surround the Achilles tendon, enhancing support and comfort. Alleviates conditions of Achilles tendinitis. Compression pad stabilizes and absorbs stress to tendon. Elastic strap provides lift to heel, helping to prevent Sudden stretch or strain to injured tendon. Fits comfortably within shoe and is to be worn during activity. Size Chart: small-large up to 6'3" X-large 6'3" and taller measurement based on individual's height. Larger ankles use X-large.