All analog warped tremolo/dirty distortion.
Controls include speed (Romance knob), blend (Honey knob), rate/drive (Fantasy), and shape/intensity (Blood knob), as well as two speed range modes, and expression in.
Limited to a run of 157, which is the catalog number of the Grooms album of the same name. It was designed by Travis Johnson from Grooms, one of the owners of Death by Audio. Here's what he says:
"I wanted to make a tremolo pedal to come out with Exit Index because, almost randomly, there is a lot of tremolo on it. I've barely used tremolo in before but came across an old Fender Princeton amp with tremolo, given to me for free, and decided to record most of the guitars with it. The tremolo on it is noisy and interesting and I used it a lot but it made me think about how I hadn't heard anything all that interesting done in a trem pedal in a while. It's one of the oldest, simplest effects. So I decided to try and make something that involves tremolo but really pushes it in weird ways. I like weird, noisy, idiosyncratic effects, so I decided to use the noisiness of that Fender amp and give it more violence, almost like a Leslie, with lots of agression and thump that can, but doesn't have to, mangle the signal. It can make really angelic, pretty sounds and alien, harsh ones too."
Note: requires Boss-style 9v adapter (not included). Does not run off of batteries.