Requires 2 AAA batteries, not included. Tested and works great.

The Korg GT-120 is a dedicated chromatic needle-type tuner designed for guitars and basses.Key FeaturesDual Display: Combines a classic analog needle indicator with a clear, backlit LCD screen.Wide Detection Range: Detects pitches from A0 (27.50 Hz) to C8 (4186 Hz), supporting up to six-string basses and seven-string guitars.Tuning Modes: Offers Auto mode (detects closest note automatically) and Manual mode (lets you select a specific note), plus a Sound Out mode for reference tones.Specialized Tunings: Supports open tunings (Open A, D, E, G, and DADGAD) and flat tunings down to four semitones below standard pitch.Built-in Microphone: Allows for easy acoustic guitar tuning without needing a cable.SpecificationsAccuracy: Detection accuracy within ±1 cent; tone accuracy within ±1.5 cents.Calibration: Adjustable from A4 = 438 to 445 Hz in 1 Hz steps.Power Supply: Powered by two AAA batteries (providing roughly 100 hours of continuous use) or an optional 9V AC adapter.Design: Housed in a black aluminum body with a built-in folding stand on the back for easy desktop or amp placement