http://www.bearfootfx.com/product/model-h/
Product Description
The Model H4K Overdrive/Distortion…the 4-Knob Model H adds a Treble control that allows the Model H to be tuned to a wider range of rigs.
The Treble control starts a little darker than the standard H and allows ample treble/upper mid adjustment. The Tone and Treble controls affect
different parts of the circuit and combine to let you get the exact impact and definition you need for your rig.
(product description lifted from Barefoot website)