Flush-M - Mercury Outboard Flushing Solution - Black - 75-450HP ModelsThe Flush M permanently replaces the OEM flush plug, making engine flushing quick and easy so you can spend more time on the water. The Flush M is specifically designed to permanently replace the OEM flush plug with the part number #22 888958001 found on late model Four Stroke Mercury Outboard Engines. Its unique features simplify repetitive engine flushing and is a must have for single and multiple engine boats alike. Flush M is compatible with