1/4" laser cut mild steel.
Sold as sets 6pcs and as many as 14pcs If you're building headers you'll need the 6 for the engine, but you'll need a few more for the collector and the rest of the exhaust system if you're doing it yourself. In our experience it will take 14 to do it right. This allows your entire exhaust system to be flanges together. No ugly muffler clamps!