This is left hand 5-string version of the monster bass, TRB series. TRB was born as a versatile 6-string bass guitar along with the greater involvement of synthesizers in music in end of 1980s. TRB has been developed to cover low tonal range with a 6th string (low B), which could not be reached by orthodox 4-string bass, and also the 1st (high C) makes possible for advanced players for further improvisation and expression.