The X10 Motion Detector, which is weatherproof, runs from 4 "AA" batteries and will work with any X10 RF receiver like the TM13 transceiver module or the REX 10 Barking Dog. It is very useful for activating a macro on the CM15 Pro X10 computer interface.

When it detects motion it sends an RF signal out which can be used to switch on any X10 device via a transceiver module. It also has a dusk/dawn facility which can be used to switch on lights or other devices at dusk and switch them off at dawn.

Note the X10 Motion Detector only transmits an 'ON' command when it detects motion, so it is not suitable for switching lights unless you want them to remain on.