The Free The Tone Iron Forest distortion stompbox features the same HTS (Holistic Tonal Solution) circuit present in the recently reviewed Gigs Boson, which designer Yuki Hayashi maintains addresses the inherent flaws in both true bypass and buffered pedal circuits.
Unlike the Gigs Bosun, instead of extra switches and options, go for four basic rotaries. No mid control might seem slightly amiss, but the bass and treble pots are very powerful, enabling you to create a metal-type, mid-scooped sound by boosting both, should you so desire. By the same token, putting them back towards the 12 o'clock position returns a more mid-rich sound.
The difference between overdrive and distortion as we've come to use the terms is not absolute, but for 'overdrive', think SRV, Robben Ford and all those thick, rounded, blues-based tones.
For 'distortion', the category this pedal falls into, move your ears to rock, and the ground between Sabbath, through Angus Young and on to the Foos and QOTSA: a harder edge, a more cutting rasp and a slightly more bratty nature overall.
Aggressive, grin-inducing, the Iron Forest is all of those things, getting fuzzy too at the upper extremes. We prefer this one with humbuckers and classic Marshall-derived amps over single coils and 'blackface' Fender-type circuits. It is definitely Rock!