Based in The Netherlands, GuitarSystems is run by Paul Lenders and Ad van Dongen (known as N.E.R.D.). Like all of the firm's range, The FuzzTool Junior is based on a vintage forbear - essentially a Fuzz Face brought up to date.
It features a matched transistor setup of a NOS low-gain silicon transistor with a medium-gain NOS Germanium transistor. Earlier Fuzz Faces were Germanium-based and later ones were silicon, but GuitarSystems says its combination retains the Germanium character and clean-up capability, with increased temperature stability (Germanium transistors are susceptible to fluctuations).
Plugged in, the Fuzz Face tone is instantly apparent, tempting you to bash out Purple Haze. There's a nice degree of touch sensitivity, and you can pull back from full-on fuzz with your volume knob. Furthermore, the TMF (Treble Mid Full) knob offers the chance to roll off some of the bottom-end for more tonal flexibility.
There are plenty of Fuzz Face clones and reissues, but this is one in a very practical form, with features that make sure it's tweakable to suit any guitar.