Silencer insert to reduce emission noise. Diameter at the wider end: approx. 47 mm (~ 1.85 inches). Diameter at the thinner end: approx. 33 mm (~ 1.30 inches). Length: approx. 200 mm (~ 8 inches). Suitable for 2 inch (~ 51 mm) manifold. Ready to install and universal use. 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.