It featured a removable hardtop that stowed in the trunk and a retractable rear window. It is available as a 2-door targa top or a retractable hardtop convertible. The stock is both retractable and foldable. The Corvette C8 convertible is the first Corvette with a retractable hardtop. The tail wheel was both retractable and steerable. It is equipped with a retractable undercarriage. The dorsal gun was mounted in a fully retractable turret. Mechanical azimuth thrusters can be fixed installed, retractable or underwater-mountable. All were fitted with retractable fin stabilizers. They can be either classified as retractable blade or retractable sheath type. Stadiums are either open, enclosed, or have a retractable roof. It also features a smaller gymnasium behind the main arena with retractable seating. A Romulan polearm, similar to a trident with retractable blades. Some aircraft with retractable conventional landing gear have a fixed tailwheel. Some feature progressive elements such as curtain walls, or retractable roofs.