"The Indoor Siren produces a powerful 104db siren and has a flashing LED light. Being a smart alarm, the SwannOne Indoor Siren has tamper protection and is completely wireless, making installation quick and easy. The siren can be configured in the SwannOne app to be triggered in a number of scenarios using the cameras, motion and window/door sensors. The siren can also cut off automatically at selectable durations of 3, 5 or 10 minutes. The siren uses D batteries, which give it a typical lifespan of more than the 2.5 years. A low battery indication in the SwannOne app will let you know when the batteries need to be replaced. "