Since the KORG AW-1 appeared, clip-on tuners have been the standard for tuning an acoustic guitar. However, some guitarists may feel that a clip tuner attached to the headstock is too distant from the eye, and that it's annoying to have a tuner attached to the headstock. KORG has responded by releasing a revolutionary new tuner. The is a unique tuner that you use by attaching it to the sound hole of your acoustic guitar. It provides an incredibly convenient viewing angle, since you can see the tuning meter within the natural angle of your sight. With a compact size, it's visually unobtrusive since it fits inside the guitar's sound hole and besides being easy to fit and remove. You need to check it out Attach inside the sound hole and tune with a natural line of sight. Fits a variety of acoustic guitars Piezo pickup rapidly and accurately detects the sound High-brightness LED for excellent visibility size:Applicable diameter 97-103mm Material:plastic colour:Black + Khaki Package Contents: 1 x Guitar Tuner 1 x Chinese and English manual Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.