Combining both the PreLine-Plus Diesel Pre-Filter and ProVent Air/Oil Separator. Direction-Plus PreLine-Plus is an innovative pre-filter system for diesel fuel systems which ensures a high degree of water separation and particle pre-separation. The PreLine-Plus kits include an intuitive multi-stage water alert that separates it from other kits on the market. The PreLine-Plus system is tailored to the most modern diesel direct injection systems for diesel engines. With a water separation efficiency of over 93% and a long service life, meeting the specifications set by leading manufactures of diesel fuel injection systems. PreLine-Plus system provides protection for all modern diesel high-pressure injection systems, reliably protecting the fuel system from corrosion, abrasion and the frequency of repairs reduced. Direction-Plus ProVent oil separator kits protect your modern diesel engine by substantially reducing the amount of oil entering the engine from blow-by gas in the crankcase ventilation system. By not fitting a Direction-Plus ProVent system, it is likely that your engine will experience a progressive reduction in performance. At 98% efficiency Direction-Plus ProVent systems, are specifically designed to separate oil from blow-by gases.