The versatile Convertible comes with 8"" rear wheels plus larger rear wheels that snap on for self-propulsion. It's like getting two chairs for the price of one. Snap off the large wheels when traveling in planes or automobiles or when negotiating tight spaces. It's lightweight and easy to fold, and can be fitted with a variety of positioning options. Its patented design provides maximum comfort and durability. Available in two models: Basic, with built-in adjustability features, and a crash-tested Transit model, for use aboard a bus or van.