Combination of GPS and GPRS/GSM wireless network Pocket-sized / light-weighted / Rechargeable battery included No external antennae needed -- Just plug-&-play

Specification:
Dual Band GPRS/GSM module (GPRS/GSM900/1800MHz)
Equipped with 20 parallel channels GPS receiver SirF III optional
Emergency alert: SOS Button

Polling function:
The supervisor can monitor the rover who is equipped with DR-TK20 by dialing phone randomly