A. Roll cages may be of two designs, low front hoop or high front hoop. All closed-top cars and cars that retain the windshield frame must have a high front hoop design. Open cars may incorporate a high or low front hoop design. High front hoops are also referred to as side hoops.

1. Closed cars: The front hoop (side hoop) must follow the line of the A-pillars to the top of the windshield and be connected by horizontal bars to the top of the main hoop on each side (as close to the roof as possible). Instead of a single front hoop, two side hoops (down tubes) may be used. Alternatively, a top “halo” hoop following the roof line from the main hoop to the windshield with forward down tubes following the A-pillars to the floor may be used. Regardless of which one of the two approved tubing configurations, there shall be a tube connecting the two A-pillar tubes at the top of the windshield.

2. Open cars: The height of the front hoop must be consistent across the full width of the cockpit.

B. Front Hoop Bracing
All open cars with a high front hoop and all tube frame closed cars must incorporate a horizontal front hoop brace at the approximate level of the dashboard. It is recommended production-chassis cars also have the front hoop brace.

1. Tube(s) may extend, from each front down tube, forward to the firewall. For Unlimited or SCCA GCR-class cars which allow it, tube(s) may extend through the firewall. In this case it is recommended this tube, one on each side, connect to the chassis at a point not more than 12 inches forward of the front axle centerline.