"An intruder came in through one of my windows late Jan 2012, was detected by the PIR,set off the alarm and fled immediately through the same window. The room needed one PIR that was free with the starting kit. To alarm the five winodws in this open plan room with extra wirless contacts would have cost five times as much. The system worked amazingly well with the 2 PIRs and 2 wireless contacts supplied but I will be now adding two more PIRs for the two rooms that have no protection currently. The Alarm (Yale HSA6400) call to my mobile phoone worked great. I was only 10 minutes away, resecured the house and went out again to continue socialising. Cannot recommend enough."