This under-cowl, in-line fuel filter fits many Mercury and Mariner outboards replacing contaminated filters and is mounted under the engine cowl. It also fits in specific Mercuries fuel filter housing. It fits the filter housings for Verado L4, L6 (serial number 2B144122 and below). It fits 1.5L and 3.0L outboards using a vapor separator system with top screw in filters. It also fits Mercuries 4.5L and 6.2L engines (serial number 2A456613 and newer.