An Aircast boot (or Aircast walking brace/walker) is a removable orthopedic device designed to immobilize, support, and protect the foot or ankle during the recovery process, often serving as a modern, more comfortable alternative to a traditional plaster cast. It features a hard, durable outer shell combined with internal air cells that can be inflated for customized, snug compression, helping to reduce swelling (edema) and stabilize injured ligaments or bones.