The EnviraStation weather station is a wireless unit operating on 2 AA batteries. This unit is great in keeping time and temperature. A great addition to any kitchen, garage or front door area before heading outside. It offers a low battery warning "beep" and is easily mountable to any surface and also can sit on a tabletop. One thing to consider when placing the outdoor sensor is not to position it in direct sunllight or too close to your gutter overhang. I made the mistake of doing this the first time and had many incorrect readings. I would recommend this unit to anyone who wants a true outdoor temperature reading even to below 0 degrees.