1. This product is fully functional, allowing it to display battery voltage and power. It can also be directly connected to a mobile phone or other 5V devices for charging. 2. This product is suitable for various outdoor power supplies, mobile power banks, instruments, and other equipment that require additional battery power voltage display and USB charging capabilities for mobile phones. 3. The front features the on/off button, while the back has the setting button for parameter installation and use. Ternary lithium battery L measurement: Charge type: L03 series to L07 series (memory retained without power) Lead-acid battery P measurement: Charge type: DC12V, DC24V (memory retained without power) Iron-lithium battery F measurement: Charge type: F03 series to F08 series (memory retained without power) Parameter: USB + Type-C interface Power supply voltage: DC8-30V Measuring range: DC8-30V Color: black Material: ABS Size: 47.6 x 28.7 x 19.4mm Package Contents: 1 x voltage meter Only the above package content is included; other items are not part of the package. Note: Light reflection and varying displays may cause the item's color to differ slightly from the actual product. The allowed measurement error is +/- 1-3cm.