Energizer Ultimate lithium 9V batteries. Last up to 20% longer in toys versus Energizer MAX batteries, and they feature leak resistant constructionand performance in extreme temperatures ranging from -40 degrees Fahrenheit to 140 degrees Fahrenheit. Use these 9 volt lithium batteries to power toys and games, or use them to provide up to 10 year battery backup in AC powered smoke detectors. Weigh 25% less than standard alkaline batteries. They also hold power for up to 10 years in storage, letting you keep a ready supply of backup 9 volt batteries.