Use with confidence! Reliability and longer life between battery changes make the Eclipse Lithium 9V Battery (1200mAh) Pack 2 a must for important devices like smoke detectors, wireless alarm systems, even garage door openers. And unlike alkaline batteries Eclipse High-Performance Lithium Batteries boast an exceptional shelf life, which means they will be ready when you need them. Note: Smoke Detectors should be tested regularly every 6 month to ensure they are operational.