The ABC is an active EQ accessory that eliminates insertion loss and is designed to work with all of EMG's non-X series pickups that use a standard passive tone pot. Insertion loss is a naturally occurring yet frustrating phenomenon that occurs most frequently with traditional balance pots, usually when it is in the middle position. It is characterized by a drop in signal strength that occurs when two competing signals are mixed; the nearer you move the balance knob to the middle position the more directly it affects the signal of the other pickup. EMG has designed the Active Balance Control (ABC) to eliminate this phenomenon and gives a player more direct control and a more reliable expectation of what their tone will sound like at any given time. Whether in the studio or playing live, EMG once again provides the reliability and quality that musicians have come to rely on the world over.B125 Active Balance Control for Bass GuitarFor Passive and Active Bass PickupsEliminates Insertion LossSolid ShaftTwo Year Warranty