Adjustable Arch Aircell. Similar to AirSport brace. High level of ankle support. Collapsed arch or flat foot. The Aircast Airlift Posterior Tibial Tendon Dysfunction (PTTD) Brace is designed to support the ankle while offering additional support with an adjustable arch aircell for PTTD, otherwise known as collapsed arch or flat foot. The arch aircell can be adjusted for individual support and comfort, along with the anatomically designed shells for ankle stability and the rear entry design with a simple two strap application really does make this brace easy to use. As an ankle brace this is very similar to the AirSport in design. There are two rigid splints either side of the ankle that go down to the bottom of the foot (and not under it) offering a high level of support to the medial (inside) and lateral (outside) ligaments of the ankle. Integrated inflation system for customizable fit, Allows patient to customize the air cell to help hold the arch in natural position.