TEKO pocket/key ring tuner for guitar or bass - Integrated microphone for acoustic tuning - 1/4" input jack for electric tuning - Key ring w/ integrated attachment - On/Off & Tuning Mode switch - Tuning modes: b (flat), # (sharp), or standard (concert pitch) - Tuning Range: A0 (27,5 Hz) to A3 (1760 Hz) - A4 frequency range: 440 - 445Hz - Power: 3V (2 x button-style AG13 batteries) - ROHS compliant - Dim (HxLxD): 22 x 52 x 20 mm / 0.9 x 2 x 0.8 in.