Rivera Buf IV A/B/Y, Gain Boost, Loop, Buffer. Designed and built by Paul Rivera of Rivera Amps and Fender before that. There were several models made, and the BUFF IV is the most difficult to find for some reason. They all "buffer" the guitar signal, hence the name.
The BUFF IV combines a great clean boost (it goes into smooth overdrive when cranked up), an A/B switcher, and a Loop Bypass (effects loop).
