The 3516E marine auxiliary engine is now available in a wide range of ratings that meet U.S. EPA Tier 4 Final and IMO III marine emissions regulations. As the commercial marine industry adjusts their operations to meet EPA Tier 4 and IMO III emissions standards, Caterpillar Marine has introduced a solution built to maximize performance while meeting regulations. Caterpillar's combination of a fuel-efficiency-optimized engine and a selective catalytic reduction (SCR) aftertreatment system is a solution that not only reduces NOx emissions, but can also lower a customer's owning and operating costs in the process.