Boost pedal
A boost pedal is perhaps one of the simplest of all gain-based pedals, boosters are exactly that. In the most cases boosters have just a single knob for gain or volume, plus a footswitch.

Treble Boosters are  the earliest compact effects pedals, In the 60s, many players used a treble booster to push their tube amp into distortion. Listen to Eric Clapton’s “Beano” recordings from 1965 to the later work of Queen guitarist Brian May.

In addition, boosters can also be used to increase the volume of your signal. Many are designed to add gain without coloring your tone at all. Some guitarists however like boosters for a subtle chime, or thickness that they add to the tone.