The Brinyte 21700 5000mAh Li-ion battery that is direct rechargeable via the built-in USB-C port. This battery is designed for high drain devices and features over-discharge, overcharge and short circuit protection. This battery can last up to 500 charge and discharge cycles. USB-C charging cable included. 

Specifications:

• Battery Size: 21700
• Battery Chemistry: Li-Ion
• Nominal Voltage: 3.6V
• Nominal Capacity: 5000mAh
• Nominal Watt Hours: 18Wh
• Charge Cycles: 500
• Dimensions: 21.44mm x 76.8mm
• Weight: 73g

Li-ion notes: All lithium ion batteries have a risk of fire and/or explosion, handle batteries with care, ensuring not to overcharge or over discharge, even if the battery contains a protection circuit. If battery is visibly damaged, stop use immediately and dispose of appropriately (Li-ion batteries pose a serious fire risk if thrown into household waste). If a battery is not to be used for over two weeks, store partially charged (30-50%) for maximum capacity retention.