Duracell Ultra Power 9V, 5 Pack.Five Pack of Duracell Ultra 9V alkaline batteries with high performance cathode technology.Perfect for Smoke Alarms. Duracell Ultra Power provides up to 40% more power vs Duracell Plus. Duracell Ultra Power batteries have POWERCHECK, an integrated tester that always letâ€s you know how much power is left in your battery. Duracell's DURALOCK technology means these batteries are guaranteed to stay powered for up to 5 years* when not being used. This huge leap forward in battery technology has been made possible by improvements in the purity of ingredients and upgrades to the construction of the battery cell meaning less power is lost when in storage.