Thomastik js 112t jazz swing .012-050 - This is the legendary flatwound jazz guitar string! A list of it's 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!GaugeJS112T - 12, 16, 20w, 27, 37, 50