The Active glass break detector MAGS-S consists of the evaluation unit and 2 equal sensors (transmitter and receiver) glued on the pane of glass. No adjustment works are necessary after the assembly. No false alarm is to be expected even at big alterations of the glass-, frame-construction caused by environmental influences like heat, cold and aging because of the automatic adjustment of the sensors to the pane of glass. The Active glass break detector MAGS-S is available for almost all types of glass within a frame construction with undamaged panes.