Spark plugs with a small diameter silver middle electrode, especially suitable for LPG and CNG fueled engines and for racing engines. The use of gaseous fuels saves a lot of money for users and is more environmentally friendly. Brisk Tábor as places great emphasis on ecology and has therefore developed a special range of SILVER spark plugs, which have been used by customers from all over the world for many years. The design of the spark plugs eliminates specific problems caused by the different properties of LPG and CNG fuel from the original installation when operating on gasoline. The high thermal conductivity of silver compensates for the increase in thermal stress without the need to change the thermal value of the spark plugs and perfectly covers the requirements of the engine even when operating on gasoline. The shape of the electrodes and the smaller electrode distance reduce the voltage requirement supplied by the ignition system. The open spark gap does not prevent the spread of the flame front and ensures perfect combustion of the mixture, which is also advantageous for the use of SILVER series spark plugs for racing engines.