Peterson R4 Wet Sump External Oil Pump, Standard Volume, Rear Drive - PFS04-1004SINGLE STAGE EXTERNAL OIL PUMP Left Side Mount Part Number: PFS04 1004 Peterson Fluid Systems wet sump pumps utilize a revolutionary twisted lobe rotor design. This design has allowed us to use all aluminium rotors saving a hugeamount of weight while also increasing performance. Our shallow depth screw in fittings make for a low profile, modular pump. Our pumps can be outfitted with numerous options as well to besuited to a variety of applications.