For F/A/B/X-body Chevy/GM cars with 283-400 SBC V8. Shorty design for power gain from idle to mid-range RPM. Fully mandrel bent tubes made of 16-gauge mild steel. Head flanges laser-cut from 5/16-inch thick steel plates. Flanges flattened by hydraulic press for precise and leak-free seal. All joints TIG welded for resistance against cracking and wearing. Black paint coating that withstands up to 500 degrees Celsius. Shorty / Short Tube. 16 gauge (1.5mm). For pre-1979 models, additional bracket may be necessary for air conditioning. Does not fit with angle plug heads or raised port heads. Note: The items you received are shown in the figure. If you have any questions later, please contact the after-sales staff in time.