The FMD is a three-in-one pedal: 1. Can function as a buffer pedal. Converts the guitar’s output into a low impedance signal 2. Can function as treble booster pedal. It's absolute magic at producing clarity and presence to solos with guitars that have a ton of bottom, or when using amps that get bloated sounding when slammed hard 3. Can function as a full range booster pedal. This mode is used to drive the front end of an amp and push the amp into its own natural overdrive