For those electronic keyboards with an input jack labeled "SUSTAIN," the FC4 model is used in the same manner the sustain pedal on an acoustic piano is used. Designed to work and feel just like an acoustic piano's sustain pedal, its specially designed rubber bottom grips the floor and stays put while you play. The FC4 can also be utilized as an FS controller for synthesizers, tone modules and drum machines. You'll be pleasantly surprised by the performance of this model!