Size LWH 85*50*4.5 mm Like an Master Card, only 30 grams, New 4.5 W GSM ID BOXNMD-330 for Earpiece2nd Generatio 60-100 CM TO EARPIECE, NO ANY NOISE, Long working TimeNMD-330(L) GSM-ID-Box, best gsm-box and most beautiful in the world, large volume longdistance, mini size only 4.5mm smaller than an Bank-card. HOW DOES IT WORKS? The new developed GSM BOX has a buildin dual band GSM module that works in both of Four Band mobile phone networks. Once insert a GSM SIM card and turn on the power, it will automatically pickup calls from any mobile phone or telephone. The powerful inductive coil will creat strong signals to drive earpieces within 40-60cm distance. One pc 35db top sensitive microphone ensures your partner hear the whisper voices, even the GSM BOX is hidden under the clothes. GSM BOX has a builtin rechargeable 650mAh battery. supports more than 3-5 hours talking time, or 8 hours Standby time Package list :1xGMS-Box1xEarphone(without battry) 1x USB charger cable