Legendary among harmonica players for its classic blues harp sound, the 520D's tradition is carried on by the 520DX "Green Bullet" and has a contoured size and shape that fits perfectly between harmonica and hands. * Volume control knob allows musicians to adjust the volume to fit each musical situation * New rugged, dynamic cartridge with improved response * High-impedance, omnidirectional * Supplied with 1/4 inch connector * Frequency response: 100 to 5,000 Hz