Features: This module boosts a single 3.7V 18650 lithiums batteries to adjustable output of 5V 9V, catering to various electronic devices like smartphones and tablets with maximums output current of 2A. Featuring integrated charging management via USB, this compactly module design includes overcharge, over discharge, and short circuits protections for enhances safety and battery longevities. Ideal for DIY enthusiasts, engineers, and beginners, this module offers easy connectivity with clear terminals, making it accessible for users of all skill levels. Perfect for diverse applications, from powering portable gadgets to integrating into customs projects, this module's small footprint ensures seamlessly integration into any setups. Equipped with LED indicators, the module provides real time status updates on charging and operation, ensuring users can monitors performances effortlessly. Specifications: Component:Plastic Size:Approx.23.4x18mm/0.92x0.71inch lnput:4.2-6.5V Output:4.2-28V adjustable Power:5W for single 3.7V 18650 lithiums batteries, fully charging with 4.2V Attention! Customers without multimeter should not buy this product. Package Includes: 2pcs 18650 Batteries Boost Converters Board(not with Protections Features) note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual item color.