Energizer 9V Max Alkaline Power Batteries, 2 Pack. These batteries offer long-lasting power ideal for smoke detectors, toys, remote control cars, clocks, and more. They have a 5-year shelf life, holding power for up to 5 years in storage for trustworthy backup energy. The 100% leak-proof construction protects your devices based on standard use. Energizer created the world’s first zero mercury AA alkaline battery, commercially available since 1991. The packaging is 100% recyclable and plastic-free.