This is a Surefire Battery, model SF2-CB.
Optimized for use in SureFire flashlights" SureFire lithium batteries pack a lot of power into a small package. And unlike alkaline batteries SureFire high-performance lithium batteries boast a ten-year shelf life" which means they will be ready when you need them" every time.
Features:
High-performance batteries, optimized for high-drain flashlights
Wide temperature tolerance
Built-in heat and fault (short-circuit) protection
