This is the Replacement Muffler for the OS BGX-1 3500 and the OS Max 1.60 FX Engines. _ FEATURES: Muffler has an internal mute which cuts down on noise output. 3-piece muffler is held together by an extremely long bolt. Comes with a pressure fitting installed. Manifold and the end of the muffler have cooling fins molded in to help dissipate the heat as it enters the muffler. The end of the muffler has an adjustable exhaust opening which can be rotated 360 degrees. _ INCLUDES: One muffler (assembled) One muffler adaptor (3/8" thick, OSMG5685) Four mounting screws _ REQUIRES: 4mm allen wrench to install the screws. _ _ SPECS: Exhaust opening at the end of the muffler: 5/8" diameter Exhaust manifold of the muffler: 1-1/4" long Length of the muffler: 9" approx. Diameter of the muffler expansion chamber: 2" _ COMMENTS: For replacement muffler mounting screws, use OSMG6931.