Fender TBX Treble Bass Expander Tone Control Potentiometer Kit
The Treble Bass Expander (TBX) is a detented, stacked 250K / 1Meg control that enhances your tonal palette. It functions as a standard tone control from 1 to 5; after 5 it decreases resistance, letting more bass, treble, presence and output flow to your amp. No battery necessary.