Nano GSM SIM Card Inductive Box for Invisible Earphone Headset Best Exam Tools
This GSM ID card (box) size is the same as ID card, so can put it into wallet or the shirt pocket.
The frequency is 850/900/1800/1900 Mhz so can work for all countries. The sim card slot only support Nano sim card.
The transmitter range from GSM card to earpiece is around 40-50cm, depends on which earpiece you use.
Build-in high sensitive microphone.
The hidden indicator can show the on/off and battery power (when charging, the indicator will blink). When you charging this device, pls make sure turn on it, then can be charged!
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