1.Solar 2-way GSM Audio Device 2.Voice-activated fuction ... standby time Solar 2-way GSM Audio Device,Audio Device,GSM audio listening device,GSM SIM audio device,This ... x 40mm x 15mmSIM Card slots - work with all GSM SIM cardEmbed condense microphone.Microphone range: about 20 Meters ... according to the pictures indication)Install:Please note that GSM network singal strength ,do no install in the ...