This BR9ES Spark plug is a BR series in economy version and the 9 indicates the heat index.
The higher the number the more it indicates a colder plug. The lower the number, the more it indicates a hotter plug.
First involved in the combustion of a gasoline engine, the spark plug plays an essential role since it is responsible for igniting the air / gasoline mixture present in the engine's combustion chamber.
This combustion creates power that will help put the vehicle in motion.