This is one of the first of the “converter comb” models produced by Rickenbacker in late 1966. It is essentially a 360-12 with a mechanism (the converter comb and arm assembly) that allows the player to dampen or mute the octave strings by engaging them with a pull-down metal comb. Although intriguing in design, it is somewhat impractical to play as a 6 string guitar, and many of this model have had the converter mechanism removed over the years. Without the comb engaged, this plays and sounds like a 12-string of the same era, but with a bit more interior wood bracing to accommodate the converter hardware.