This is NOT a copy of the Butler, only based on the design. With that said, it is an amazing sounding heavy overdrive. Just don't expect any clean sounds with soft "on the edge of breakup" from it. Starved plate, like most of the actually tube driven pedals, you can honestly find the same sound in most high gain diode clipping overdrives that don't need 400 mA power supply. I still love it for what it is. Put it in front of a dirty tube amp ;)
P.S.: don't forget to cut the power to it after use, or it's going to keep heating the tube (and the casing). The foot-switch only engages the bypass.