Description Nobody knows flatwound bass strings better than Thomastik-Infeld. SPIROCORE series have been legendary among upright bassists for decades. Now the electric bassist can also experience the Thomastik-Infeld sound by utilising a highly pliable steel core which is wrapped with a silk inlay. The outer winding is a true ribbon flatwound constructed of a special nickel alloy. The result has an incredible depth of tone and an enhanced fundamental which is unavailable from any other flatwound string.