Sierra's 18-2566-9 Impeller Gaskets are designed for use in Mercruiser Alpha I Gen II and Mercury 75 HP, 90 HP, 100 HP, and 115 HP outboard engines. The package includes two impeller gaskets. They are interchangeable with Mallory 9-60023; GLM 30290; Chrysler/Force/US Marine 27-817277; Mercruiser Stern Drive 27-817277 and 27-8172771; and Mercury Marine 27-817277 and 27-8172771. Check manufacturer recommendations to ensure a proper fit before purchasing. Each Sierra product meets or exceeds the original equipment part it replaces.