The ER26500M/ST is a cylindrical lithium-thionyl chloride cell manufactured by Ultralife. This 3.6 Volt primary battery has a capacity of 2700mAh (milliampere-hour) and provides a very high energy density of 972Wh/L (watts per liters). The battery is ideal for use in a variety of applications due to its small form factor, long shelf life, and safety features. With a wide operating temperature range of -55°C to +85°C, this battery can withstand extreme temperature ranges, making it suitable for temperature-sensitive applications. Other features of the ER26500M/ST include high reliability, low self-discharge rate, and excellent charge retention. This makes it suitable for applications that require high reliability, such as in medical, automotive, emergency lighting, and telecommunications equipment.