An extended-range bass is an electric bass guitar with a greater frequency range than a standard-tuned four-string bass guitar.One way that a bass could be considered 'extended-range' is to utilize a tuning peg that allows for instant re-tuning, such as the popular 'Xtenders' made by Hipshot, however it is more so those bass guitars that have a low-B string such as the five string bass guitar and/or a high C-string - the six string bass guitar - that are most normally considered extended-range bass guitars.