The Electro-Harmonix Q-Tron+ envelope follower pedal takes a great design even further! In addition to the original Q-Tron's great features and sound, the Q-Tron+ gives you an effects loop that lets you put an additional effect between the Q-Tron+'s preamp and filter section without changing the envelope drive. An Attack Response switch has also been added, allowing you to choose between the classic fast response of the original Q-Tron and a slower, smoother attack. If you're looking for some ultra-cool, funky and active filtered tones, check out the Q-Tron+! This unit is used and is in great condition. Functions flawlessly, and sounds great!