Protects silencer packing during washing# Turning the handle expands the plug Silencer plugs are great for keeping water out of your exhaust pipe when washing your bike or when its in storage. Silencer Plugs extends the life of your pipe and it looks cool too! Our man Richard once caught his small son stuffing his pipe with rocks ... \"Look, daddy, I pushed in 22 stones into the bike to give it extra power\" .... Yea, right, avoid the hassles of life when it is this cheap. 2-Stroke application.