Three, I don't really care if you believe me or not, but as I said mine is a 1/4 540 and the other three were Lasers. Fact are facts, and although it is weird, that 4 airplanes all had the same problem, it happened whether you chose to believe it or not. I suggest you get one, and when you have problems, call Bubba at Lanier and then tell me what kind of experience you had. Be sure to ask for Bubba.