The driver’s side of the car with the side cage installed. The lower “X” ties together from two bulkhead crossmembers of the Factory Five frame, and also ties in the longitudinal chassis crossmember via the vertical tube. Part of the design was to fit between the seat and the 
body without interfering with the driver. This structure is permanently welded in for greatest strength, while the upper bar attaches via a clamp on the roll hoop.