In the words of JHS Pedals:

The JHS Pedals 3 Series Compressor is a simple and powerful compressor
that will give you everything from subtle tone smoothing to a super
squashed sound. The Attack and Sustain knobs allow you to dial in the
compression’s overall feel and response to your playing, while the
Volume knob enables you to set the overall volume at unity or boosted.
The Bright toggle engages a brighter EQ so that your tone doesn’t get
lost in certain situations.