Exhaust gas catalytic converter (catalyst) is a device in the exhaust system of a vehicle which is designed to reduce emissions of toxic exhaust gases by means of reduction of nitrogen oxides and the use of obtained oxygen for final combustion of carbon monoxide and unburned hydrocarbons.

  The catalyst consists of a ceramic or metal capsule (a honeycomb) covered with precious metals such as platinum, palladium, rhodium, and a metal protective housing. The cars are equipped with two types of catalysts: ceramic or metal. Ceramic catalysts are more common on the market due to their lower prices. But the ceramic capsule is not very resistant to mechanical impacts.