Universal Security Instruments Battery-Operated Ionization Smoke and Fire Alarm, Model 2975 Powered by a 9-volt battery and is easily replaced with Quick Draw battery drawer (battery included) Audible low-battery indicator gives battery change warning reminder sounds for up to 30 days Fast and easy to install with no wiring required  Responds quickly to protect against deadly threats Single silence/test button makes it easy to quiet non-emergency alarms and test alarm functions  Offers two tamper-resistant locking features Comes with a three-year limited warranty