This is a replacement o-ring for the JW12 3 Port and 5 Port engines.
This is the second o-ring that seals the base of the carburetor and the carburetor retaining bolt.
This o-ring is located inside of the crankcase at the base of the carburetor, just below the retaining bolt.
Crankcase Carb O-Ring (15x1.5) (for all JW12)
