A USB power bank is a portable charger that provides extra battery life to your mobile devices. It is a small, lightweight device that can be easily carried around and used to charge your phone or other electronic devices while on the go. The most popular type of USB power bank is the Levo PA71, which has become a very popular choice for those who need extra battery life for their mobile device. It works by storing energy from an external source such as an AC wall outlet, car charger, or solar panel and using it to charge your device when needed. This makes it a great option for those who are often on the go and need access to power when they are away from home or work.