This is a 500 series JFET limiter distortion unit with two knobs and two switches making it quite simple to operate. The first switch takes you from limiter mode to crunch mode and the second changes the release from slow to fast modes. The input knob and output knob are pretty self explanatory. Sound quality is pretty good in that it doesn't muck up the sound in limiter mode and it does what it's supposed to in crunch mode....add harmonic distortion. The only reason I didn't score it higher is the noise. When you switch to crunch mode the noise increases as you raise the input. It's been said the unit is quieter than the original Shure Level-Loc, which this is based on, but I don't own that unit and so can't compare. Regardless, it can get noisy when pushed. It could pose a slight issue if you have to stack tracks or the unit is in crunch mode at any quiet point in the song. If music is going on it's not going to be a issue. If tape hiss doesn't bother you then this won't either. Regarding features it doesn't have many but you know that when you purchase this type of unit. It's great for adding distortion to vocals, some hair to bass lines and keys, and smashing some room mics for drums. I feel a bypass switch would have been immensely helpful. This is probably it's main shortcoming. Overall, it's a cool distortion unit and comes in handy when I'm looking for an aggressive crunchy sound.