Depending on the specific application, there is an appropriate control technology to meet the desired emission reduction. The primary control technologies which are currently available for on and off-road applications include oxidation catalysts, 3-way catalysts, SCR catalysts and particulate filters. Oxidation catalysts are ideal for lean spark ignition (SI) and compression ignition (CI) applications while 3-way catalysts are appropriate for rich burning SI situations. SCR catalysts can be applied to both SI and CI engines and is used to reduce NOx emissions. Particulate filters, often referred to as diesel particulate filters (DPF) do no react with exhaust gases but filter out particulates within the exhaust stream in CI application.