D'Addario NS Micro Clip Free Tuner

This tiny tuner stays tucked away by screwing into 1 of your guitar's tuning machine screw holes (screws included; see pics!).

The tuner has a piezo transducer which picks up the vibration to let you know when you're in tune.

It has a back-lit LCD full color display (great for dark environments) and can act as a visual metronome as well.

It can be used on electric guitars, basses, mandolins, banjos and other stringed instruments.

Calibration range from 410 to 480Hz.

Makes a great gift for any guitar enthusiast!