Excellent quality and durability to improve vehicle performance. Shorty design for power gain from idle to mid-range RPM. Fully mandrel bent tubes made of high quality 16-gauge 304 stainless steel. Head flanges laser-cut from high quality 3/8-inch thick steel plates. The flange is flattened by a hydraulic press for precise and leak free sealing. All joints are golden color TIG brass style welded to prevent cracking and wear. Flanges chrome plated for corrosion resistance. Polished surface for extra protection against rusting. The accessories in the photos are included. Header Type: Shorty / Short Tube. Primary Diameter: 1-5/8 in. Collector Diameter: 2-1/2 in. Head Flange Thickness:3/8 in. Pipe Thickness: 16 gauge (1.5mm). Material: 304 Stainless Steel.