ER2801B Features Mini A8 GSM/GPRS/GPS tracker Perfect for home monitoring， children， old people， personal supervision monitoring， car， and warehouse security tracking Features sound control and dial function Use dual mic and IC control  Sound control: SMS 0000 to turn off， 1111 to turn on Not suitable for 3G mobile phone Emergency call: SMS SOS LBS positioning: Edit capital letters DW or GPS machine number， a minute or so， will return a message containing the address / latitude and longitude / URL information General Specs Type GSM / GPRS/ GPS Tracker Connection GSM / GPRS GSM Frequency 850/900/1800/1900 MHz Charger Input AC 110-220V 50/60Hz Charger Output DC 5.0 V/500 mA Battery Chargeable 3.7V 500mAh Li-ion battery Storage Temperature Minus 40 - 85 degrees Working Temperature Minus 20 - 55 degrees Humidity 5%-95%  Product Details (without package and accessories) Dimensions 43.2 x 32 x 13.6 mm  Weight 30 g