The A23 battery (also known as 8LR932, 8LR23, GP23A, MN21, V23GA, 23AE, L1028 or ANSI-1181A) is a dry cell-type battery mainly used in small electronic keychain radio devices, such as keyless vehicle entry systems, home security systems, garage door openers, and Bluetooth headsets.
An A23 battery is cylindrical, smaller than an AAA battery, measuring 28.5 mm long and 10.3 mm in diameter, with a typical weight of 8 grams. An A23 battery is an 8-cell device with a nominal voltage of 12 V. The higher voltage is necessary for the radio frequency-transmitting and receiving devices which A23 batteries often power. It has a capacity of around 55 mAh. 
A23 batteries are constructed of 8 individual LR932 alkaline button cells enclosed in a wrapper.
The A23 battery is close in size to the N battery, which has a voltage of 1.25V to 1.5V.
- "Duracell Technical Library".
- Shenzhen Power Stations Limited - 23A specification (PDF) http://www.power-stations.com/editor/uploadfile/20087119118513.PDF