This is specially replacement muffler for... Harbor Freight Predator 670cc V-Twin... What is included in your order? 2 Exhaust, right and left + High quality hardware ( You can use the original nuts on your predator 670 too!) -Type of application Universal (Example) Tractors, Generators, Go Kart etc. Exhaust flange is CNC cut 1/4" thickness Type of material is mild steel (Heavy duty exhaust) (((Sandblasting plus 2000F high heat primer has been applied))) Muffler OD 2" ... thinner tube OD / 1.25") Wall of the tube is 1/16 Muffler (Exhaust is a solid piece along with the muffler! Made in the USA (Top notch quality! ENGINE NOT INCLUDED.