You don't have to leave lights burning all night in order to offer your guests a safe walkway and prevent potential intruders from sneaking up to a darkened home. The Freewire Motion Detector has a fully weather-resistant case to protect the sensor from the elements, and it can turn on lights automatically when someone walks onto your property, thus providing a sense of security as well as giving your guests a fully lit path to walk up to your door. Using wireless radio frequency (RF), the FWMD sends signals to any Freewire or X10 Base Transceiver (sold separately), which then passes them on to your house wiring, all in fractions of a second. The FWMD can save energy by turning lights on only when it detects motion in the dark; if you prefer, you can set it to transmit every time it sees motion, even if it's not dark. The light will automatically turn off when it no longer detects motion for the length of time you specify, between 1 and 256 minutes. A locking screw prevents the easy removal of batteries, so you can rest easily, knowing your home is safe and secure. The FWMD requires 2 AAA alkaline batteries, sold separately more info