The Spring Tank gives you the ability to create the perfect spring reverb for your sound with controls for Depth, Length, Highs, Boost (to control your overall volume), and two independent and switchable reverb mixes called Tank 1 and Tank 2. The Depth controls the size of the room, while Length controls how long the reverb reverberates. Highs gives you the ability to control the tone of the reverb by adding or subtracting high frequencies. Tank 1 acts as your main reverb mix control, while Tank 2 is your secondary mix control engaged by the Tank 2 switch. So you have two reverb mix options on the fly! JHS also added a Boost control so you can regain any perceived volume loss from the reverb.