Darkglass Vintage Microtubes Bass Overdrive w/ Power Supply and Patch Cables 4 Knobs for ultimate flexibility while keeping the format light and small Blend: Allows to mix exactly how much clean signal you want to mix with the Overdriven. Drive: Sets the amount of gain for this pedal. The Vintage Microtubes gets a lot cleaner than the Microtubes B3K, but do not worry; there is still more gain than youll probably know what to do with. ERA: Interacts beautifully with the Drive knob in order to recreate some of greatest landmarks in rock and roll bass history ERA: Interacts beautifully with the Drive knob in order to recreate some of greatest landmarks in rock and roll bass history!