Amazon.com: M-Audio EX-P | Universal Expression Pedal for Keyboards & SP 2 - Universal Sustain Pedal with Piano Style Action For MIDI Keyboards, Digital Pianos & More : Everything Else
M-Audio EXP Express Pedal
Amazon.com: M-Audio EX-P | Universal Expression Pedal for Keyboards, MIDI Keyboards/Controllers and Supported Guitar Effects Pedals : M-Audio: Everything Else
Daisy-chaining a MIDI expression pedal with a footswitch for added capabilities - YouTube