Even that is saying too much. It's vague, nontechnical and invites follow-up questions, and implies you're the type who'll tamper with the aircraft in flight.

Even that is saying too much. It's vague, nontechnical and invites follow-up questions, and implies you're the type who'll tamper with the aircraft in flight. It's also repetitive enough to come across as improvised. "As a private investigator, I use this tool to...investigate privates." I'd flag you. Sibling comment nails it-- "it's a wireless signal analyzer." Gets right to the point, sounds legit and implies safety through read-only operation.