Wi Ex - the YX400PCS / zBoost One is the only cell phone signal booster with NO EXTERNAL ANTENNA--Just a one piece unit that sits in a window and covers approx. 1200 sq ft. **Operates ONLY on the Sprint or MetroPCS networks** Increases indoor signal coverage up to 1200 square feet or 1 - 2 rooms, Supports 1 to 4 users operating on the same carrier network, Easy to set up just put it where you get signal and plug it in, Extends phone battery life (uses less power when signal is stronger) and Protects the operator's network using patent pending technologies