A roll cage is a specially designed protective frame built in (or sometimes around) the passenger compartment of a vehicle. Generally made of welded steel tubing, a roll cage is a safety feature in the event of a rollover or crash. Roll cages are used mainly in auto racing and off-road sports such as rockcrawling. The roll cage also stiffens and adds strength to the vehicle which improves handling. When the cage is constructed on the outside of a vehicle it is usually called an "exo-cage".