Alertme Lifesaver Alert - Driver Alertness System Main Function: Anti-fatigue alarm device. Alarm Mode: Sound alert with On and Off button Ergonomic design: Compact and lightweight (1 oz) alertme fits comfortably behind ear Battery operated: Replaceable button cell battery. Life Time: 30000 nods Safe to use: FFC approved, CE Certified and Mercury free Alertme Lifesaver Alert - Stay awake and stay alive; Avoid drowsiness while driving; Mercury free and FCC approved