This is a Maxon AF-9 envelope filter. I used this for about 20 mins in my home after I bought it but other than that, I have not used this at all. This is a really nice, wet and funky filter and many say is the closest thing to a Mu-Tron other than an actual Mu-Tron. It comes in the original packaging and is in basically mint condition. there is a very small chip on the paint on the left side of it but it was there when I bought it. These pedals go for about $190 brand new. I'll take $130 shipped (+$5 for international shipping). No trades.