Product installation: put the tail throat directly on the Triple-cornered car tail mouth, use a wrench to tighten the screw until the tail throat can not be pulled out. Convenient and quick (Note: The Triple-cornered car exhaust pipe outer diameter 38-54mm can be directly screwed, and the Triple-cornered car exhaust pipe outer diameter 55-60mm is recommended to be fixed by welding.) There is no instruction included.Professional installation is highly recommended Specification: Inlet size (inner diameter): 60 mm Outlet diameter: 76 mm Overall length: 220 mm Colour:black Material:stainless steel Package Contents: 2 x Exhaust Muffler. Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.