In the words of Reuss Musical Instruments:The Reuss Repeater Fuzz Mk IV marks a return to the two-in-one pedal concept of the old Mk I and II. The pedal features a fuzz part and a repeat percussion part, each with their own dedicated footswitch and level control.The Repeater part of the Mk IV is identical the Reuss ‘stand-alone’Repeater pedal, which means it features an added the MIX control (clean blend), which was not part of the vintage Vox Repeat Percussion effect. The mix control makes it a more useful and less extreme tremolo effect, because the amplitude of the spikes can be watered out by mixing the effect with the clean sound. Still, you can have the pure, undiluted full-on psychedelic stutter when you need it (MIX control all the way down).