Its twin dynamic ﬁlters combine to give a phased wah-like 'whowh' effect for bass guitarists looking to add a mean funk vibe to their sound.
As it's got just one adjustable Response control you'll only need about ten seconds to get the hang of it (and another couple of minutes to ﬁnd the sweet spot to suit your playing style).
The ﬁlters are responsive, so the harder you attack those strings, the more pronounced the effect is. The other control is a Dist switch that gives a 'harmonically enhanced' (aka mildly distorted) version of the effect.
Although you probably won't ﬁnd yourself relying on the Bassballs as a core element of your sound, it's a worthy addition to a bassist's box of tricks to use as a standout effect on a track, or to enhance selected notes or phrases.