Nickel flatwound with a round core. 36" scale. Gauges: .044 - .057 - .072 - .096. Gauges 45-65-80-105-130. Stainless steel roundwounds. Long scale. The original roundwound bass string, utilizing specialized materials and a unique manufacturing method giving this string unsurpassed brightness, sustain, and string life. Jacos favourite by far! Rotosound is famous for their high quality electric bass strings.