A swell pedal of a slightly different variety that you have to play to appreciate.
Most swell pedals on the market are either auto swells or manual pedal volume controls. The Black Howler is somewhere in between.
The Howler has 2 knobs, the first of which sets the volume you want to start at. The lower the volume you start at the bigger the swell. The second knob controls how long it takes the swell to reach its apex. From a range of 0 to about 10 seconds. The stomp switch is actually a momentary switch that as long as you are pressing it the swell is activated. When you let off the switch the swell immediately returns to its starting volume.
Well, now you're probably saying, "well, I can do the same thing with the volume knob on my guitar," and it's true you can. The big difference though is when you set up the Black Howler the way you want it, it will repeat those settings of intensity and time delay exactly every single time you hold the switch down. It's probably not the kind of pedal you're used to, and that makes it perfect for experimenters of all genres.