A Diesel Exhaust Gas Purifier / Scrubber is a device which initiates a chemical oxidation reaction and allows the reaction to proceed at lower temperatures than otherwise possible. Purifier / scrubbers are flow-through devices which the exhaust gas is directed into a catalytically coated honeycomb core. At relatively low exhaust gas temperatures the exhaust gas pollutants are catalytically burned (oxidized). Pollutants such as CO and HC are catalytically reacted with oxygen. The net result is that harmful CO and HC react with oxygen to form relatively harmless CO2 and water. http://www.bartellmorrison.com/file_library/downloads/37_ULE.pdf