[simonbarker87]

In the UK, signalling alarm systems (those that ring the police and so are actually useful) require that 2 types of detection technology be used in the one senor. Microwave and passive IR.

Using these together significantly reduces the chance of a false positive than just using one type on its own.

So, you could use this to replace the microwave sensor in the dual tech sensors but you would still need the PIR.