All of our battery-equipped instruments feature active electronics. For our battery-equipped guitars, the battery compartment is used for a 12dB push-push active volume pot. The following guitars have a battery: Majesty models, JP150, JP157, Luke, and Valentine models.For our battery-equipped bases, the battery compartment is used for an active EQ (Preamp / On board electronics). All basses have a battery except for our StingRay Short Scale.