This is a complete set for electronic Earpiece. The battery backup of this product is not that huge but can work 1 to 2 hrs. 

How to use this device K577  - 
Insert SIM card into this device and the device will turn On automatically.
Then insert the cell into the earpiece and keep the device keep to your ear and wait for 30 to 50 seconds.
 
Now make any call to that SIM number and it will be picked up automatically.
You will be able to listen to the person and MIC is there in the flat box K577 and it's highly sensitive.
 
Box contains - 
1 Flat box basic model K577
1 Earpiece 
2 Earpiece cell 
1 charger and Cable 
 
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