Duracell Alkaline MN21 Specialist Batteries are ideal for use in a wide variety of electronic devices such as digital cameras and camera flashes, portable lights, medical devices, electronics, laser pointers, microphones, night vision devices and security devices such as electronic locks. The cylindrical shaped battery measures 28.5 x 10.3 mm, and is also referred to as a LRV08 battery, which is found in everyday devices such as watches, calculators, clocks, torches, toys, car fobs and door chimes.