A. All portions of the roll cage subject to contact by the driver must be padded with a minimum 1 inch of material. Padding that meets or exceeds SFI 45.1 or FIA 8857-2001 (curved padding), or SFI 45.2 or FIA sports car head rest material (flat padding) specification is recommended.

B. No portion of the roll cage may have an aerodynamic effect by creating a vertical force.

C. The radius of all bends in the roll cage (measured at centerline of tubing) must not be less than three times the diameter of the tubing.

D. It is recommended that all joints of the roll cage be welded. All welding must include full penetration, no cold lap, no surface porosity, no crater porosity, no cracks, no whiskers, and so forth. Welds shall be continuous around the entire tubular structure. Procedures for welding alloy steel shall be in accordance with accepted industry practice. It is recommended that a certified AWS D1.1 welder do all welding.

E. It is recommended that gussets be used at all joints.

F. Any number of additional tube elements is permitted within the boundaries of the cage structure. Such tube elements may pass through any mandatory or optional bulkhead or panel separating the driver/passenger compartment from the trunk/cargo area/fuel tank/fuel cell area provided the bulkhead is sealed around such tube elements.

G. Removable roll cage bracing is acceptable in one of the following configurations.

1. If one tube fits inside another tube to facilitate removal, the removable portion must fit tightly and must bottom by design, and at least two (2) bolts must be used to secure each joint. The telescoping section must be at least 8 inches long. The minimum bolt diameter is 3/8 inch.

2. Removable bracing may incorporate connectors of the double-lug, double ear-type, tapered or muff-type. The double-lug type must include a doubler, gusset, or capping arrangement to avoid distortion or excessive strain caused by welding. Double ear-type joints must be fully welded at all the mating surfaces.