I use this tuner mostly on acoustic guitars.
The poly tune mode and the single string mode does not correspond. When the strings have been fine tuned using the single string strobe mode (which is by the way really accurate) i strum all strings, the tuner goes to poly tune mode and indicates that three strings are out of tune. So the poly mode is useless, at least on my guitars.
Never mind, the display is clear, the two single string modes are good, accurate and easy to use and the clip is steady without damaging the finish of the guitar. I like this tuner and I am happy that I bought it.