This is a compressor in compact pedal format offering a lot of the control you would expect from a studio compressor, in other words attack, release, ratio (presets) plus input level / threshold and output level controls. All the controls do what they are meant to do and it certainly compresses as expected, however it just isn't transparent and changes your sound and not for the better. You do get a punchier fatter sound, depending on how you set it up of course, but it changes your tone and you lose the character of your instrument. Maybe that's ok for some and depending on your rig maybe you won't notice, but for me it changed things too much so I didn't keep it.