Impellers are critical to engine cooling systems, take a long a spare. Mercury outboard engines rely on the water pump for cooling. The impeller is the heart of the water pump; inspection and replacement is required on a regular basis to keep the engine running at optimum temperature. Quicksilver impellers give boaters and technicians the confidence of using an OEM part. Each impeller is engineered to original Mercury or MerCruiser specifications to provide a factory fit and restore function to factory specifications. Because impellers can be quickly damaged by running through silty or sandy water or by being run dry, we recommend having a spare aboard to be ready for unexpected failures. Available in many sizes for different engine applications, reference your repair manual to confirm the proper part number for your inboard or outboard engine. Or call 1-800 BOATING with your serial number, or make, model and year of your engine and speak to an expert to find the right impeller. Key Features Engineered to original Mercury specifications Quicksilver is an OEM part and will restore function to factory specifications Compatible with 18hp, 20hp and 25hp Mercury, Mariner and force outboards; call 1-800 BOATING with you engines serial number to be certain this impeller is correct for you outboard