This is the replacement carburetor sealing washer for the O.S. .61 SX-H and the .61 SX-H. It is constructed of aluminum. PACKAGE INCLUDES: One washer SPECS: Inside diameter: 12mm Outside diameter: 18mm COMMENTS: This is the washer that goes between the crankcase and the rubber carburetor gasket. If the customer wants the gasket, use OSMG6229. 3-29-94/eke