The simplest and most precise tuning APP with auto noise filtering. First step is choose the frequency at top of screen, then choose the tuning at the middle of the screen. When you play instrument, the pitch will be shown on the panel for the individual string by indicating signal high or low.[Function Description]A4 Frequency adjustment: choose 430~450 frequencies for A4 string.The scale for precision tuning is 10 cents for every sub-bit. The green arrow means pitch is accurate and it will turn white once the pitch difference exceeds more than a sub-bit.The complete function, will visually tell you the pitch is good or not by lighting green or white. Users can easily adjust the string by the lighting arrow shown on the scale.