This is a DOD FX25 Envelope Filter (2 knob version from the 80's I believe). I bought this off fellow TB'er Markjazzbassist who is a great guy BTW. Anyway, I decided I'm not going to mess with FX right now so I am unloading this envelope filter. It has been used and shows signs of usage but is still functional. It is missing the battery compartment cover but it has an adapter for the 9V battery if you want to run it in your power chain. I'm asking exactly what I paid for it which is $40 shipped. No trades (maybe a phaser).
