Thomastik Jazz Swing JS112 jazz strings 12-50. This is the legendary flatwound jazz guitar string! A list of its players reads like a Jazz Hall of Fame, and it's still the undisputed king of flatwounds, for many of today's jazz greats. A true flatwound (not a "ground wound" or "compressed wound" like some of the pretenders) with glassy smooth polished nickel winding on a round core, it has the perfect balance of fundamental to overtones required for traditional jazz. Some players claim that its mellow, powerful tones actually improve with age!