WERMA optical-audible combination signal devices use both elements of sight and sound to indicate processing stages, risks and potential dangers. With the optical portion, the relative importance of the action to be taken can be indicated by color as well as by the light effect and length of the signal being used. The customer can choose from a whole spectrum of signals ranging from the permanent light to the more intensive blinking light through the rotating indicator or the attention-getting flashing light. While the audible portion is where caution, prudence and clarity are essential, and are used to indicate emergencies and demand direct action. They are understood throughout the world regardless of culture or written language. Signaling with audible devices works via one or more tones or tone sequences.