This little green envelope filter was one of DOD's best sounding pedals. The simple two knob design and well voiced effect has made this a lo-budget classic. While DOD has replaced this model with the more versatile FX-25B, this one is still worth picking up if the price is right. The range and sensitivity dials are responsive and after a little tweaking, playing, and then tweaking, you'll be ready to rock and or roll. The beauty of the envelope filter is that most of the control is actually in your picking and own expression. With the exception of an actual wah-wah pedal, this clever effect responds to your playing like no other. The units weve tried performed wonderfully and held their own against units far more expensive. At some settings, the FX-25 comes gleefully close to sounding like the Mutron II or the Electro-Harmonix Q-Tron.