EQ-20 Advanced EQ

Programmable Graphic Equalizer

World’s first programmable 10-band graphic digital equalizer pedal for guitarists, bassists and other live performers
9 internal memories for storing user-created EQ settings
Level switch for connection before amp or in effects loop (+4dB)
Professional sound quality using superb A/D-D/A converters
Single-purpose design; simple user interface

https://www.boss.info/us/products/eq-20/