The four different functions; horn, engine noise, flashing light and siren sound can each be triggered by pressing the pushbutton. The respective function is immediately switched off by pressing the button repeatedly. The auto switch-off function is triggered after approx. 18 seconds. 2 standard AAA type batteries are included. The siren sound can also be switched from the American version to the European version with a switch in the battery compartment. The module is suitable for all MAN and MB Actros trucks as well as MB Unimogs (not included).