understanding volume pedal impedance

[alhbass]

Apologies if there's already a thread, but I did search before posting...

Just looking for some guidance about the meaning/significance of high or low impedance with regard to passive volume pedals - I'm looking at the Boss ones in particular, but couldn't find anything to explain it on their website either.... Advice would be appreciated- thanks.

[itu]

If your bass is hi-Z ("passive") AND the vol pedal is after the bass, your choice is a hi-Z pedal (250 k or similar).

If the volume pedal is after some fx pedal, so later in the chain, you may use a lo-Z unit, no matter the bass output.

If you have a lo-Z bass (so called "active"), go for a lo-Z.