The Energizer CR2025 button battery is one of the most commonly used 3V lithium cells in devices ranging from key fobs, 3D Glasses, Calculators, Medical Devices, Remote Controls, Toys to computer memory backup. This convenient single cell pack from Energizer gives you a reliable power source now.. Due to their lithium chemistry, you can set one of these batteries aside as a spare for up to 8 years. The lithium make-up also means these cells are very light in weight and extremely temperature tolerant, performing reliably at -20C to 60C.. It is 20mm in diameter and 2.5mm thick.