OMC Replacement Fuel/Water Separating Filter - These are the replacement elements, thread on style, for Sierra standard filter heads. Sierra High Performance series fuel water separator filters eliminate harmful contaminants as well as removing 99% of emulsified water. Sierra fuel filters are engineered for stern drive and inboard engines along with 2-cycle and 4-cycle outboard high and low pressure fuel systems. Due to the rise of ethanol blended fuel the gasoline stored in the tank is prone to rapidly absorbing water and breakdown of fuel stability. Preventing water, dirt, and other contaminants from entering your engines fuel system is key to maintaining a strong running and efficient engine. Poor fuel quality leads to knocking, rough running at low idle and fouled spark plugs. These pre-fuel filters mount easily in the fuel line between the tank and engine. Micron 10 filter. Replaces: OMC #502905 OMC thread. 1 per package.