Volume & Expression Pedals
The Boss FV-500H is a mono volume pedal with a high impedance that can be used for many purposes, but mostly for guitars and guitar effects. If you want to use it with keyboards and stereo effects, you will need the FV-500L.
You can use the EV-5 volume pedal perfectly as additional pedal for the Roland/Boss guitar multi effects and of course as expression pedal for key instruments.
Fender EXP1 expression pedal with cable.