Silencer insert to reduce emission noise. Diameter at the end of each: approx. 48 mm (~ 1.89 inches). Length: approx. 330 mm (~ 12 inches). Suitable for 2 inch (~ 51 mm) manifolds. Ready to install and universal. This dB killer dampens the sound of the bike down. This avoids trouble with residents and the regulatory authorities. The typical sound is naturally preserved.