A Roll Cage is a welded structure of tubular steel inside the vehicle that protects the driver in a rollover or impact. Beyond safety, a properly designed cage substantially increases chassis torsional stiffness, allowing the suspension to function more precisely. Roll cage specifications are governed by sanctioning bodies — SCCA, NASA, NHRA, and others — with specific tubing diameter, wall thickness, and joint requirements. A roll bar is a simpler subset; a full cage extends through the dash and into the front of the car.