Action Tuners String Master guitar tuner
As you pluck each string, the String Master automatically tunes your guitar by turning each peg with its motorized robotic grip.
I used it to tune my band's electric and acoustic guitars.
THE REAL DEAL
Although it adequately tuned the electric, the tuner sometimes took 30 seconds to find the correct pitch for a single string on the acoustic. Worse, it completely detuned my E string and tightened my G until it broke.