2V 3V 5V 6V 9V 12V DC Piezo Electronic Buzzer Very Load Alarm Electric Security Siren Horn 120dB@12VDC

I don't know how they can get such a loud sound out of such a small package but this thing delivers. Be very careful when testing this, it is loud enough to damage your hearing when close to it. Makes an excellent burglar alarm, should drive them away. Put one of these in every room of your house and they won't be able to tolerate being in there. I almost took off a star because of the plug and no documentation. But simplest is to just cut it off - however that would prevent you from returning it if you decided it wasn't loud enough ha ha. Anyway I found that tip is positive and the sleeve is negative. It survived having the voltage reversed. I only tested it at 12 volts. If it is too loud for your needs then you should be able to reduce the voltage for less volume.

I have a stand alone remote controlled motion alarm. I plugged this siren in and mounted it in the next room. Installation done. This little siren is loud. It is a different pitch than my other alarm and between the two it is uncomfortably loud. I definitely recommend this siren if you have a device that it can plug into. All the wifi smart security system cameras are great for helping the cops find the perps after your house has been robbed or you have been killed. A few now have sirens in addition to all their cameras. Did you know that you can buy wifi jammers on the inter net that nullify your wifi security system? Buy a couple of battery operated or battery backup stand alone non wifi old school motion alarms for the rooms where your outside doors are. Even high tech crooks don't like loud alarm noise.

I bought this as part of a DIY FloodLight system that I'm building. This will be the siren that I will be able to trigger, either by motion or remotely. I had no idea what to expect really. I received it and took it out of the box and was impressed with the build quality - I was expecting something much cheaper feeling. For the price it's actually well constructed. Next, being impatient, I just grabbed a used AA battery (maybe it had ~1.2V charge on it) and just connected both ends of the siren to it (after snipping off the 3.5mm jack connector - save it for later if I need it). Even at 1.2V it had decent volume and was good to alert someone indoors in the same vicinity. Probably not going to hear it out doors but I was impressed that even at 1.2V it was a respectable "noise" level. I then got out my power generator and connected it up and started cranking the voltage up - after around 2.2V it became VERY loud. I increased it to 3.3V (which would be the output level of my esp8266 mcu) and it was VERY LOUD, almost to the point where i needed some ear protection. My wife started nodding - yeah, that's definitely going to frighten away anyone nosing around our front porch. I stopped there because I was indoors. I'm shuddering to think (in a good way) how loud this will get at 5V, or even the full 12V. So very pleased with this unit, so pleased that right after this review I'm going to buy another 1-2 units. It's nice to know I could potentially power it from a single AA battery all the way up to a full 12V. Highly recommend!

This siren is rated for 12V, but it's already uncomfortably loud at just 3.3V. I'm hesitant to run it at the full 12V.

I have purchased several piezo buzzers in the past that were supposed to be very loud only to return them because they weren't satisfactory. I purchased this one for a replacement liftgate alarm on my van. Now when I open my liftgate it sounds like a large earth mover backing up. It clears the parking lot so I have it to myself. This thing is loud, I will probably wrap it in foam to quiet it down. Very happy with the purchase and as always Amazons service.

As I stated above, I found some of the comments funny but most of them appear to be spot on. I am using this little thing as an added sound effect to my pipe organ (yes, pipe organ!) For that reason I need to limit the power to 5v dc. Yes it's plenty loud if not annoying at 5v never mind 12 which I do not plan on ever using. Again all depends on where it gets situated and installed.

This thing is loud. I clipped off the aux cord plug and wired 2 of them to a toggle switch, and then to a 12v 40 watt transformer with power plug. The alarm on my security system is a joke. This can be toggled at will and is right by my security monitor. I'm sure it could be heard from blocks away. Can easily hear it inside with doors closed. It is smaller than i expected but works great

I cut the connector tip off, and touched the leads to a rechargeable AA battery (1.2V) it was loud enough to be heard. Then I tried an alkaline AA (1.5V). I was surprised that it was noticably louder. The I tried 3.7V 18650 Li-ion battery. That was loud enough to hurt the ears. If I use 5V on it, it just might be too loud for my project!