A single Excell 9 volt alkaline battery in a blister pack. The 9V block battery (IEC 6LR61, listed by the supplier as LR61) is the rectangular battery with snap terminals on top, used in smoke detectors, multimeters and test equipment, guitar effects pedals and wireless microphones, some toys, remote controls and electric fence testers. Alkaline cells last longer than zinc-carbon 9V batteries and hold their charge well in storage, so it is worth keeping one as a spare for the smoke alarm or meter. Do not store a 9V battery loose with coins or keys, as the terminals sit close together and can short. Single use only, do not recharge, and take used batteries to a recycling point.