The Fastway Exhaust Wash Plug is designed specifically for use with Fastway Spark Arrestor End Caps. Available in Small and Large sizes, they help keep your muffler packing dry during washing or transport. Don't forget to remove before operating the motorcycle! Large: ~1.5625" plug diameter. Small: ~1.25" plug diameter. Precision engineered, machined, and assembled in the U.S.A. 6061 billet aluminum construction. Rubber O-ring seal. Parachute pull-cord.