Includes a system of internal baffles that separate the oil from the air, then returns the oil back to the engine. It mounts upright on the alternator stand making for easy oil filling. Designed to look like part of the engine. The Billet Aluminum filler cap seals with an O-ring. Aluminum construction offers great looks and leak-free operation featuring an O-ring seal and Button-head Allen topscrews. Vent your valve covers, crankcase or air cleaners.