Cummins' Tier 4 Interim Clear Advantage lineup features 3.3- to 15-L engines, ranging from 60 to 600 hp (45 to 448 kW). The six-cylinder QSB6.7, QSL9, QSX11.9, and QSX15 offer more than 173 hp (129 kW) and meet U.S. EPA Tier 4 Interim/EU Stage IIIB regulations. An integrated Cummins' particulate filter aftertreatment system removes particulate matter (PM) emissions by operating with passive regeneration without impacting performance. In the 75- to 173-hp (56 to 129 kW) category, the four-cylinder QSB3.3, QSB4.5, and lower rated QSB6.7 use the company's compact catalyst, a passive, exhaust flow-through aftertreatment for smaller equipment, to remove PM. The B3.3 Clear Advantage engine covers the 60- to 74-hp (45- to 55-kW) range without aftertreatment, exhaust gas recirculation (EGR), or electronic controls. A cooled EGR system is featured on all engines above 74 hp (55 kW) to reduce NOx emissions by lowering combustion temperature.