Just like the Duracell plus 9V battery, the Duracell Ultra 9V battery has a shelf life of up to ten years but is 40% more powerful than the Duracell Plus 9V battery. This battery is one that is used in low energy draining devices such as smoke alarms, this means they need replacing less frequently. This fantastically reliable 9V battery is available in this single cell pack to buy in multiple quantities as well as just the one single cell pack, all at equally cost effective prices.