This Jalo Kupu Dark Grey 4-Pack includes 4 smoke detectors that combine functionality and appearance. The smoke detectors detect smoke and look great thanks to the satin finish. You attach the smoke detectors to the ceiling using the included adhesive tape, so you don't have to drill into your ceiling. You can easily turn on the smoke detector with the press of a button. When the sensor detects smoke, it sends out a signal with a sound of 85 decibels. The smoke detectors do not require any wiring to operate. Each one runs on 3 batteries (included) and has a lifespan of 10 years.