From the sealed lead acid battery such as the 12/6v sealed lead acid, the 9v PPE or the more domestically well known Duracell AA, AAA, C battery, D battery - and many others besides.
To be used in devices such as a smoke detector, a heat detector and a carbon monoxide alarm(a device that detects the presence of the carbon monoxide (CO) gas in order to prevent carbon monoxide poisoning).
