The Muc-Off Exhaust Bung is made from a two-part flexible silicone rubber core and sleeve. It creates a leak-proof seal to prevent water or other contaminants from getting into your exhaust pipe while you’re cleaning or maintaining your machine. Thanks to its removable two-part design, it's both 2- and 4-stroke compatible. It’s ultra-easy to twist into place and has a handy lanyard to make removal easy. The tapered design means it fits most exhaust diameters, is made from ultra-durable silicone rubber, and protects your engine. Before use, ensure the exhaust is fully cooled. For a 2-stroke exhaust remove the black silicone sleeve from the bung and for a 4-stroke exhaust, and keep the black silicone sleeve on the bung. Just insert and twist the exhaust bung into the end of the exhaust to form a perfect seal, and then your bike is ready to be cleaned without the risk of damaging your engine. Always remove it again before starting your engine.