This 1/2 AA Lithium Thionyl Chloride battery is ideal for wireless alarm systems such as the MCPIR-3000, memory backup for computers like the Apple Macintosh (Parameter Random Access Memory, Parameter RAM, or just PRAM), high tech Suunto dive computers, some Aladin Dive Computers, most ITI, Radionics, ADT Alarm Transmitters and DogWatch 3000 Invisible Fence Systems. Lithium Thionyl Chloride has the highest energy density of any practical Lithium battery chemistry, three times greater than Alkaline (Zinc Manganese Dioxide) batteries. It also has the widest operating temperature range of -55°C to + 85°C. Self discharge is low at less than 1% per annum at 20°C, giving an effective shelf life of 10 years.