[i4n]

I've brought back ESC and Transmitters in the past (as well as a Losi XXX-CR and spares) with no problems.

I put them in my hold bags still in the boxes, making sure they were on the top and put the receipts next to them. My bags were opened, but by the TSA in the USA and not the UK and (they put a leaflet in the bag to let me know) but everything was pretty much where I put it. I guessed that as they were obvious what it was (box and receipts) that they were happy.

I (rightly or wrongly) just walked through the green channel on my return looking innocent!

This was 5/6 years ago so things may have changed now and someone else might give you better advice.