The Nitecore NL1840 is a high performance 4000mAh rechargeable button-top battery designed for use in high drain devices including the EC23, Concept 1 and TM28. This battery has advanced safety features like a microporous barrier protecting internal components and nickel plated stainless steel protectors offering external protection. High performance internal circuitry prevent overcharge, over-discharge and short-circuiting to keep you and your devices safe.