The AirCast AirHeel, with its amazing aircell technology, massages away heel pain as you walk. You will feel the massaging compression and support of AirHeel with every step. Interconnected aircells, located under the arch and in the back of the heel, exchange pressure to ease swelling and discomfort from plantar fasciitis, heel pain and Achilles tendonitis, while helping improve circulation. Made of lightweight, breathable neoprene, this easy slip-in design features an adjustable hook-and-loop closure for a comfortable fit in seconds. Must be worn over a sock.