Smallest GSM BOX and Spy earpiece - eletronic earpiece.
Battery backup - 2 hrs 
Distance between earpiece and Signal Box is 30 CM 
earpiece size - Standard - Totally invisible from outside ear 

Earpiece works upto 4 hours with asingle cell.

earpiece cell model - 416
 
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.