I got my first siren yesterday. It is made in Hong Kong in the 1960s or 1970s I am guessing. & it is a 8 port single tone. I got it running on two double AA batteries & it sounds like a smaller version of a full size siren. At full 6 volts it is ment to scream. Even at 3 volts it is loud. I am very happy with my find. Sirens big & small are rare to find in my area. I am thinking of trying to repair the broke area where the battery terminal is or just getting a new battery holder to run this siren. The clip with the stop is a trigger for if it was stuck in a window or door jam. & when both ends make contact it sets of the siren to scare a intruder. If it were dual tone & had 12 ports also on it, it would have sounded like a mini Alerting Communications of America, American Signal Corporation Cyclone, P50/ T135 & have a perfect 5th.