Duracell MN21 (A23) Batteries (x2)

The A23 battery is a small feat of miniaturisation: under its cylindrical casing are actually eight micro-cells stacked together, which lets it deliver a high 12 volt voltage in a tiny format (28.5 mm long and only 10.3 mm in diameter). It is this combination of high voltage and compactness that explains its success.

Called A23 by Energizer and MN21 by Duracell, this battery goes by many other names depending on the manufacturer: 23A, 8LR932, GP23A, V23GA, LRV08, MN21/23... but it is always the same format and the same voltage. You find it in a host of household devices: gate and garage door remotes, car keys and remotes, wireless doorbells, alarm and keyless entry systems, timers and some shutter remotes.

Its high voltage goes hand in hand with a deliberately modest capacity (in the order of a few dozen mAh): the A23 is therefore designed for very low-consumption devices, used in short pulses, where it ensures a good lifespan. Like all alkaline batteries, it is single-use and not rechargeable, and should be recycled at end of life in battery collection bins. From Duracell, this version benefits from the brand's quality and long shelf life. Sold in a pack of 2, it is the battery to keep in advance so you are never left stuck in front of a gate or a car.