Gearank

From manufacturer:

Unzip your soul! Just picture your guitar signal being massaged by a complex set of filters moving through a vacuum tube maze. Energized by two Electro-Harmonix 12AX7 tubes, the Tube Zipper's patented moving filter tastefully adds controlled analog harmonics to your signal. In typical EHX fashion, each control can be set over-the-edge, generating a host of novel tones. Tron or Trill a la mode!