Tone Control, BTC System for bass, Separate Bass & Treble Pots. For EMG pickups only, the BTC System features a pre-wired balance control (blend) and master volume with the bass and treble on a concentric pot. BTC Controls and Systems are the most widely used bass EQ Systems in the world. Approximately 12db of cut and boost are available for bass and treble and all controls are center detented to assure quick return to normal tone settings. A dual-dip switch is mounted to the PC Board that lets you program the high end frequency response four different ways so you can choose the sound that's right for you. These systems use the latest in surface mount technology, are extremely quiet, and require very little current from a 9 Volt battery. Package Includes: 2 concentric knobs and 2 knobs for balance/master volume.