Its a security system...
it sold as conforming to std part of that std requires anti tamper circuits,
if your the sort of person that lives alone, has no friends or guests visiting, never has any tradesmen ect in the house then the anti tamper feature on the sensor can easily be removed using a soldering to blob out the the switch on the pcb
If you have co. which does not maintain systems & sells the engineering code..... err I think you may be dealing with "S Hit Alarms Ltd;"