Use to plug the end of your silencer while washing your bike Made of soft rubber Small one for 2-strokes and larger version for 4-strokes, please specify. Silencer plugs are great for keeping water out of your exhaust pipe when washing your bike or when its in storage. Silencer Plugs also extends the life of your pipe and they just look cool too! Available in 2 sizes. Small is 40mm and fits most two strokes 50cc to 500cc. Large is 65 mm and fits most four strokes.