The Hi-Fli consist of several sections. Those on the left half are Top Boost, Octave Shift (containing Sub-Octave and Ring Modulation features) and Sustain Fuzz. Then a Bypass Mixer (mixing wet/dry signals) divides the left and right parts, the right half consists of probably the most important part as regards sound shaping, a wonderful multi-feature Phase Filter. I also added two features that appeared on the original Hi-Fli Mk2 units: a bypass front panel slide switch to bypass the left hand side effects completely and send the audio signal directly into the Phase Filter (very useful!) and an additional ‘Growl’ switch that drops down the fundamental note extracted from the audio in by two and three octaves (The Sub-Octave drops it by one octave). These sub-harmonics are not just combined with the original sound but used to modulate the phase filter thus allowing very strange/bizarre new sounds to be created.The pedal unit is a fantastic idea. All the front panels sliders simply provide a control voltage to operate each effect… yes all the effects are voltage controlled! On the bottom of each slider is a 3-way slide switch marked '+','0' and '-'. In the '0' position the pedal has no affect on the effect as you operate it and the slider acts as the effect control. In the and or - position operating the left or right pedal sends a control voltage that swings from and 12V to -12V or -12V to and 12V as you move the pedal up/down. The left/right pedals control the left/right hand effects when viewing the top panel. Since there is an independent pedal slide switch on every effect you can imagine the creative possibilities here! There are many many different sounds you can create simply by altering the state of each pedal voltage slider switch. This is a really great idea and is why I said earlier that the pedal unit, in my opinion, is crucial to getting the most out of the Hi-Fli.