Fit 99-06 Chevy/GMC trucks and SUV (2WD & 4WD) 4.8L, 5.3L, 6.0L. Full length design for power gain from mid to high RPM range. Long transition collector for decreased back pressure. Fully mandrel bent tubes made of 16-gauge 304 stainless steel. Head flanges laser-cut from 3/8-inch thick steel plates. Flanges flattened by hydraulic press for precise and leak-free seal. Flanges chrome plated for corrosion resistance. All joints TIG welded for resistance against cracking and wearing. Polished surface for extra protection against rusting. Long Tube / Full Length. 16 gauge (1.5mm). For track/off-road use only. No instructions provided; professional install recommended. Note: The items you received are shown in the figure. If you have any questions later, please contact the after-sales staff in time.