Supports 5V-18V (10W-30W) solar panel input with reverse polarity and backflow protection Charges 3.7V Li-ion 18650 batteries (BMS optional, not required) USB output: 5V/2.1A with low-voltage cutoff protection Battery level indicator activated by button press MPPT technology for higher charging efficiency Features: Supports 5V-18V (10W-30W) solar panel input with reverse polarity and backflow protection Charges 3.7V Li-ion 18650 batteries (BMS optional, not required) USB output: 5V/2.1A with low-voltage cutoff protection Battery level indicator activated by button press MPPT technology for higher charging efficiency Quick Guide: Set the jumper to match your solar panel's voltage before use. Connect the battery, ensuring correct polarity. USB output requires a battery to be connected for stable operation. Press the button to check battery level and activate USB output after charging. USB will automatically turn off when battery is depleted and will not restart without pressing the button. Note: Do not use USB output without a battery connected. Color: As Shown Material: PC Package Contents: 1* Module Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.