The main hoop acts as a foundation for the entire rollcage, as it serves as an attachment point for the door bars, halo bar, trunk bars, shoulder bar, and kicker bars. Per NHRA specifications, it must be within 6 inches of the driver's head, a minimum of three inches above the driver's helmet, and at least as wide as the driver's shoulders. Buck measured from the center of the headliner toward the B-pillars to determine where to bend the bars. Buck shoots for 1/8-inch of clearance between the hoop and the headliner to prevent rubbing and squeaking. On a street car, the position of the hoop may need to be tweaked slightly to prevent covering up the dome light.