The dp musicworks Tremble-O is a full-featured photo-coupler based tremolo pedal. In addition to the normal rate and depth controls, it has a rotary selector with four oscillation wave forms to choose from. They are square, triangle, ramp up sawtooth, and ramp down sawtooth. It also has an interval control which adjusts the on-off timing of the oscillations, as well as a boost control to compensate for any perceived volume loss. The rate control features a large black aluminum knob for easy foot operation. A yellow LED monitors the oscillator at all times, while a red LED indicates if the effect is engaged or bypassed. The Tremble-O is powered by a 9-volt battery and comes finished in hammered light green with a matte black bottom. It also includes true bypass switching and an AC adapter input (adapter not included). It's overall dimensions are approximately 3-1/4" x 4-1/2" x 2-1/4".
The Tremble-O is $199.00 plus shipping and applicable tax.