The SB7 tone-lok synth pedal - you know the one; silver brick with the knobs you can push in to lock in place. It's basically an envelope filter with a built in fuzz you can turn on (synth1/synth2 on the mode switch). Note: I found that the Short decay setting requires a pretty hot signal so it doesn't slam your notes down to nothing, so use something that really pushes out the signal if you want to use that setting. Velcro on bottom from previous user. Older unit so it isn't pristine but it's in good shape.