Make every girls' room safe and fun at the same time as the Elro FS8110 Elven princess. Besides that this smoke detector looks nice with the princess, he also makes the nursery a lot safer. The optical sensor detects smoke and fire. At the moment of detection, an audible signal sounds 85 dB. The built-in lithium battery lasts up to 10 years. Although you do not have to think about it, it is important that you regularly test the detector (on average once a month).