The Korg CA-40 is a slim, compact chromatic tuner with a large, clear display that's perfect for all sorts of instruments. Strings, brass, and woodwinds can tune up using the built-in microphone without the use of microphones or other equipment. Similarly, electric instruments can connect via the input and output so you can leave the CA-40 connected between your instrument and amplifier. If you prefer to tune by ear, use Korg's "Sound Out" function to tune against the reference pitch of your choosing.