Some of our friends acros the puddle will know this story- I know of someone in the bat research community who put an expensive bat monitoring ultrasonic recording system under a bridge in London. The police did not know what it was and their bomb disposal unit disrupted it. The owner did not put any identification marks on the outside of it. It cost about the same as a
M2P.
I put my name, phone number and registration number on the top of my
M2P with a sharpie pen, hoping if ever necessary, someone will return it and not destroy it.