Werma signaltechnik led buzzer combination 450 with acknowledgement function werma signaltechnik 450 100 55 p the werma signaltechnik 450 100 55 is an led buzzer combination 450 with acknowledgement function for an as interface reg the combination unites a very bright light signal with the powerful sound of a buzzer by gently pressing the front surface of the product the audible signal can be turned off in a matter of seconds this acknowledgement signal is fed back to the master via the