The Fender two button pedal that is....I've had this amp for 20 years and I used to have a 1974 Super Reverb that I had "blackfaced" for several years but neither had the pedal. Since I got this back from Kevin Nelson and it sounds better than ever I decided to order the pedal for it when I ordered my new gig bag (Mono m80, yo!) and I tried it in class last night. Having the amp trem handy is pretty cool and it is a great sounding trem to boot. Not sure how often I'd use the reverb button but its cool to have. The amp with those few pedals is a pretty nice sounding rig now....