Seymour Duncan SA-1 Acoustic Tube Stack Demo. The Acoustic Tube SA-1 is a quick mount passive and magnetic soundhole pickup which will fit in spaces between 3.85″ to 4.10″ and features hum-canceling, lower impedance, a flat tone and a built-in easily-accessible volume control.
It comes with a short cable and female 1/4″ output jack that can be connected to a standard guitar cable and then to an amplifier, PA or console.