Air / Fuel Regulator Diaphragm For Mercury Optimax Left Rail 2.5l

Fits 2.5L (135 - 175 HP) or 3.0L (200-300 HP) Optimax Engines ONLY. This diaphragm is used in either regulator (fuel or air) on the port side fuel rail for the 3.0L (200 - 300 HP) engines, and for the fuel regulator in the port side rail for the 2.5L (135 - 175 HP) engines.