https://www.amazon.co.uk/dp/B010NE3ND8/ref=pe_3187911_185740111_TE_item

Just bought micro SD cards SanDisk extreme 16GB for £13.47 each and discovered that I had the remains of a gift card reducing the price further. Happy days.

Thanks Andy. Our order arrived safely today. Play time.

I've got some nice little circuit board boxes to stick my detectors in. I'm going to ask a question which I think I know the answer to, but if I don't ask it, I'll end up being wrong. Is the "entrance" for the microphone that little hole in the centre of the microphone symbol on the circuit board?