The Achilles Shield insole protects the Achilles tendon area from the abrasive rear edge of stiff new shoes and boots. This is the most common form of foot discomfort and injury caused by footwear. Leather shoes, especially new ones, have rigid top edges that can painfully rub against the back of your foot with every step. This often results in bruising, blisters and abrasions. The Achilles Shield puts something between shoe uppers and the sensitive part of your feet; so you can break-in your shoes without breaking in your feet.