Features: [Strong compatibility]: for 18650 batteries, supports 3.7V and 4.2V output when full, suitable for a wide ranging of devices, such as wireless keyboards and mouse. [type c port】]: Adopts type c port, supports two-way insertion and fast charging, providing a more convenient charging experience. [Overcharge protections]: intelligent protections circuitry prevents overcharging, over-discharging and short-circuiting, ensuring safe battery use and extending battery service. [compactly and Lightweight]: Mini size design, compactly size, easy to integrate into various devices to save space and enhances portability. [Indicator Function]: Equipped with LED indicator, it can display the charging status in real time, which is convenient for users to know the power status at any time. Specifications: Material: Metal Size: about 10x7.5x5.2mm/3.94x0.3x0.21in Purpose: Suitable for intelligent wearable devices, Quantity: 10pcs Package Includes: 10PCS Charging board note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.