The Mosky F-DER is an amp simulator pedal for guitar, based on Fender amplifiers and designed as a clone of the Tech 21 American. It allows you to bypass your amplifier and connect directly to a mixer or audio interface without losing the warmth and character added by the speaker.

The F-DER can also be used to add more depth to a dull-sounding amplifier or to adjust its tonal profile. It is intended for players seeking the classic American guitar sound associated with Fender amplifiers.