From Electro Harmonix;

The Bass Clone chorus pedals core circuitry is nearly identical to the
legendary Small Clone chorus, but with added features especially for
bass. Chorus is a combination of modulated and dry signals. The Bass
Clones Crossover switch cuts low end from the modulated signal so the
pedal delivers a more accurately articulated bottom end with excellent
note definition. The Treble control affects the whole signal while the
Bass control only affects the dry half. Together with the Crossover
switch they provide precise sound shaping that lets you achieve a tight,
focused bass guitar sound with a well-defined low end and shimmering
chorus on top.