Single black nylon tapewound bass guitar string. Specifically designed and patented in 1962 to emulate the mellow sound of an upright bass using flatwound black nylon ribbon, our Tru Bass strings have been embraced by players of all styles. Originally conceived by James How to be fitted to the Burns Black Bison bass, Tru Bass strings may be the nearest you will ever get to a double bass tone from an electric bass.