Fender TBX Tone Control Kit, 0992052000

As used in the Eric Clapton Strat

TREBLE BASS EXPANDER, Check out this book for wiring diagrams!

This is a novel tone upgrade control that does a little more than what you already have in your guitar. The name of the TBX tone control comes from an acronym for "Treble and Bass Cut" (cut = "x" in Fender-speak). A conventional tone control only cuts the high end of your guitar's signal. However, the TBX can either cut the high end like a regular tone control *or* it can cut the bass to bring out more brightness in your tone.

In the middle position (e.g., "5"), the tone control is at a "10" relative to how most tone controls read. In other words, it is bypassed. Now, when you turn it to 10, you cut the bass and effectively increase the prominence of the treble in your tone.
Conversely, turned to 0, the TBX sounds just like a conventional tone control turned all the way down. The nice thing is that Fender makes these such that the potentiometer finds a little resistance groove at 5, so you know exactly where the middle position is when you turn it to that spot.