Gauges 40-60-80-100. Flatwound. Rotosound Jazz Bass Strings are the original monel flatwound bass guitar strings. One of the original Rotosound sets from the early 1960s. These strings can be heard on many famous albums, used over the years by Sting, Phil Lynott, Steve Harris and John Deacon. Rotosound makes the world's most famous and highest quality electric bass strings.