This is a complete set - 
Once insert a GSM SIM into the neck loop Tabiz then the device will start automatically , it will automatically pick-up calls from any mobile phone or telephone.
Two-way covert communication via mobile phone networks 
Optimized inductive coil creates strong power for earpiece
Size 85*50*4.5 mm* *8 to 9 Hrs model is having extra network booster and having the most powerful mic and its size is 1 mm more than the rest models
The battery backup depends on the variants you choose. 
 
To use the electronic earpiece your ear canal has to be clean so that the small electronic earpiece could smoothly go inside the mid canal of the ear properly and safely. This electronic earpiece has cells inside, and the battery life of these cells are 4 hours. The cells need to be replaced after their life. Electronic earpiece are slightly bigger in size compared to magnetic earpiece and are louder than magnetic earpiece.
 
Cautions - 
Don't use this earpice for longer time. 8 to 9 hrs is maximum use time since it's electromagnetic ways might harm if exposed for longer durations. 
Never sleep with magnetic earpiece in your ear
Do not insert forcefully. Don't push the earpiece as they might harm your ear canal/drum. 
The buyer shall not use the product for any illegal purposes and shouldn't permit anyone to use the product in any kind of unlawful activities. We promote our products for betterment for our lives not to go against law, or humanity.