And the red and green LED indicators are nice for low light situations

You can then turn off the sound and accurately tune with the LCD meter or LED indicators, either with the built-in mic or by plugging your electric guitar or acoustic mic directly into the tuner

In other words, no B, C, D, F, E sharp, Open A, Open C, Open D, Open F, Cross Note C, Cross Note D, anything that requires you tune a string to C or F.To put a simply, no experimenting, which is pretty much the only reason I can think of to buy a tuner.