A neighbor just bought one of these but no reports yet on it's performance.

Seems ironic though that it claims to notify you of a visitor if your gone. You will likely trip the alarm when you leave and when you return. Unless you park your vehicle beyond the sensor, go inside reset it, then leave, and then go check sensor when you return before you trigger it driving  back in the lane.

 http://www.lowes.com/lowes/lkn?action=productDetail&productId=17607-46035-51316&pad=true