It is made of electronic accessories, nickel plating on surface(anti-oxidatioan), inner conductor: pure copper.it is long lasting and durable for you to use.

Parameter:
Charging voltage: DC 4.5V-5.5V (DC 5V recommended)
Charging current: 0-2.1A
Charging quiescent current: 100uA
Full voltage: 4.2V+ -1%
Discharge current: 0-2.4A
Discharge quiescent current: 50uA
Discharge efficiency: up to 96%
Output voltage: 5V
Output current: 0-2.4A
Ambient temperature: -20℃ to + 85℃
PCB board process: Shen Jin
Size : 25 * 16 * 4mm

The module comes with lithium battery protection function：
Over-current protection (OCP)
Overvoltage protection (OVP)
Short Circuit Protection (SCP)
Over-temperature protection (OTP)
Charge and discharge power level 4 interval indicati

Pin description:
VIN: Charge Port Positive Input +
GND: Charger Negative Input -
BAT: Lithium Battery +
GND: Lithium Battery -
GND: Output Negative Output -
OUT: Output Positive Output +
KEY: Output Enable Trigger Port (Low Pulse Trigger)

Applications:
Car charging retrofit
Driving recorder power supply
Mobile power
Portable devices such as mobile phones and tablets

Package Including:
4 * 2A 5V Lithium battery charging protection module