The CR123A 3V Lithium Battery is a common battery used with wireless devices. Brand may vary from picture.
DURACELL HIGH POWER LITHIUM CR123 BATTERY 3V
CR123A 3V Lithium Battery - SafeHomeCentral
Honeywell 1321 16.5VAC, 25VA Plug-in Transformer - SafeHomeCentral
CR123A lithium battery, 3 volts with 1400 mAh, 3,50 €
DURACELL HIGH POWER LITHIUM CR123 BATTERY 3V
DURACELL HIGH POWER LITHIUM CR123 BATTERY 3V
8 Best CR123A Battery For Smoke Detector
Honeywell 5816: Installing the CR123A Battery
CR123A 3V Lithium Battery 1500mAh 2 Pack, 123 Batteries Lithium, 123A Lithium Batteries 3 Volt High Power, CR123 for High Intensity Flashlight, Home Safety, Security Devices 1 Count (Pack of 2)