SEM Robert Bosch in Stuttgart Germay was the inventor of the spark plug an the high voltage magneto for high reving combustion engines. This was patented in 1902. All ignition systems before that had not been depandable enough. In Bosch system an induced high voltage generated a small spark between two electrodes on the spark plug. The first Bosch magnetos were introduced in Sweden 1905. Bosch patent was however not strong enough and could be rounded and competitors entered this big market. SEM begun producing magnetos in 1916. From 1934 SEM also produced flyvheel magnetos. SEM is still in business today.