A fourth push button control is available on American-made Jazz Basses produced between mid-2003 until 2008. Known as the "S-1 Switch", this feature allows the pickups to operate in standard,
parallel wiring, or alternatively in
series wiring when the switch is depressed. While in series, both pickups function as a single unit with one volume control, giving the Jazz Bass a sound more similar to the Precision Bass. The two pickups are built to be opposite from each other in both magnetic polarity and electrical phase, so that when heard together, hum is cancelled -- the
humbucking effect.