OEM Mercury Marine Outboard 4-Stroke Under Cowl Inline Fuel Filter An in-line fuel filter located under cowl on outboard engines. Fits the 4/5 hp. 2-cycle (1999 & newer), the 4/5/6 hp. FourStroke (1999 & newer), the 8/9.9 hp. FourStroke (2005 & newer) and the 15/20 hp. FourStroke (351cc, 2008 and newer). Please email us your engine model or serial number prior to bidding if you are unsure if this is correct part.