Main Features: 
Multifunctional Testing Tool, it can measure voltage, current, discharge flow, also includes timing, over flow and voltage protection 
Small size,easy to carry and store, you can use it anywhere and anytime 
The screen displays current and voltage data for easy viewing 
With automatically save data function when interruption of power supply 
Measuring Method: 
USB input port is plugged in 5V charger, USB output port is connected to mobile phone, directly read the current and voltage parameters 
Measuring Micro USB line quality: USB output port is connected to mobile phone, USB input port is plugged in the 5V charger first, remember the voltage, then Micro USB input port is connected to 5V charger, remember the voltage. The smaller the voltage difference, the better the quality of the Micro USB line 
Use TP4056 and other linear charging circuit, through this capacity table, to fully charge the battery with completely no power, the capacity data is the battery capacity, and using this method, you can also test the mobile phone charging capacity 
Connect this testing tool to portable power source and turn on it. Press the button until the capacity data is zero. Insert the cell phone to charge until the portable power source switches off automatically. The next time you open this testing tool, the display capacity is the portable power source output mAh 
Parameter: 
Voltage ( input / output ) : 4V - 30V 
Current ( input / output ) : 0A - 3A 
Test capacity range: 0 - 99999mA 
Accuracy: + / - 1 percent 
Input: USB 2.0 Micro USB 
Output: USB 2.0 
Application: Computer,Mobile phone 
Package weight: 0.047 kg 
Product Size(L x W x H): 7.30 x 2.80 x 1.50 cm / 2.87 x 1.1 x 0.59 inches 
Package Contents: 1 x USB Detector