The BAT-1/3N-GP is a 3-volt, 1.2Ah lithium thionyl chloride (LiSOCl2) primary battery that is part of the GP brand of batteries manufactured by GP Batteries. This battery is known for its long shelf life, high energy density, and low self-discharge rate. It is widely used for commercial, medical, and military applications. The battery has an expiration date, making it slightly more expensive than other GP batteries. It is identified by its standardized, three-digit series of numbers and letters, known as the North American Nomenclature System (NEMA). In this case, the BAT-1/3N-GP stands for BATtery, 1/3 cell size and GP brand. The NEMA code for this battery is 1/3N.