Secure power for the long haul. This Rayovac® 9V lithium battery is perfect for use in smoke detectors, home security systems, and other devices that need long-term power. With a specially formulated high energy density, it lasts up to 10 years in smoke alarms to save you money and provide peace of mind. Battery Type: Lithium; Battery Size: 9V; Voltage: 9 V; Material(s): Lithium.