The Sierra 18-2945-9 Drain Screw Gasket is used with the 3/8-16 drain/fill screw found on all Mercruiser and most Mercury/Mariner O/B's, along with most lower units and sea water pumps. It is interchangeable with the following: Chrysler/Force/US Marine F8186, F50556, F8077, 12-19183, Evinrude/Johnson 307552, Mallory 9-60101, 9-60102, Mercruiser 12-20260B, 12-19183B, 12-20260, 12-19183, 12-191832, 12-191833, Mercury 12-191833, 12-20260, 12-19183, 12-191832. Each drain screw gasket meets or exceeds the original part it replaces. Fit specific, check part numbers before purchase to ensure proper fit.