The 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 Verado, Pro XS, FourStroke, and SeaPro series e