From the manufacturer:

Bad Stone Phase Shifter

EHX has resurrected the legendary Bad Stone Phase Shifter. With prices of 1970s’ vintage Bad Stones soaring, now is your chance to get a reissue that is faithful to the original circuit design and three-knob control layout, but features up-to-date enhancements for the modern player.
The Bad Stone delivers an incredible six stages of phase shifting plus a manual mode that lets the player freeze the phase. Its Rate knob controls the phase shifting speed which goes from a very slow swoosh to a rapid, oscillating warble. Feedback determines the depth of the phase effect and a toggle switch lets the user select Auto or Manual modes.