It's a 5000mAh TR 16340 3.7V Lithium-Ion Battery. The 5000mAh TR 16340 3.7V Lithium-Ion Battery is a compact yet powerful energy storage solution. With its impressive 5000mAh capacity, this rechargeable battery can deliver a reliable and long-lasting source of power for a variety of devices and applications. Its 3.7V output voltage ensures a stable and consistent supply of electricity, making it suitable for high-drain devices such as flashlights, digital cameras, and portable electronics. The lithium-ion technology employed in this battery offers excellent energy density and a low self-discharge rate, ensuring that it remains ready for use even after extended periods of inactivity. Its compact size and rechargeable nature makes it an environmentally friendly choice, reducing the need for disposable batteries and helping to minimize waste. Whether you're a tech enthusiast or an outdoor adventurer, the 5000mAh TR 16340 3.7V Lithium-Ion Battery is a dependable and versatile power source for your devices.