The 3S 18650 Lithium Battery Capacity Indicator Module Level Tester with LED display is designed to visually show the remaining charge of 3-series (11.1V/12.6V) lithium battery packs. It uses a clear LED bar graph to indicate battery levels, making it ideal for e-bikes, DIY power banks, battery packs, and other lithium-powered devices. Compact and easy to install, it provides real-time monitoring to prevent over-discharge and maintain battery health.