SystemStak Welcome to SystemStak from Eaton: a revolutionary, compact system for sandwich mounting modular valves between a directional control valve and a standard mounting surface. SystemStak gives users a full range of complementary pressure, flow and check valve functions, while saving space, reducing installation costs and increasing efficiency in hydraulic systems. Features Smaller package size saves space and improves system design flexibility Reduces installation costs and improves operational efficiency Eliminates external leakage and boosts resistance to contamination for better overall reliability Provides easy access for service and maintenance