I once carried 2 x headsets, 1 x plb, 1 x 296 Garmin, 1 x medium mag light and a set of halogen bike lights with bike drink bottle battery that says in the instructions to not take it through airport screening because it looks like a bomb. Thought I'd test the waters. It worked; every time I went through the checkin a yellow box came up on the screen warning them that the package was suspicous, same too with the PLB but no rejection for carry-on. Interestingly when the battery and PLB were placed upright in the bag as it went through there were no alerts as the profile was quite skinny I guess.