The loudest, most expressive strings ever created. Provides increased output, frequency response, and strength. M-Steel, short for Maraging Steel, is a superalloy used in high stress applications for the aerospace and defense industries. The wound strings are comprised of a patented Super Cobalt alloy wrapped around a Maraging steel hex core wire, producing a richer and fuller tone with powerful low end response. M-Steel plain strings are comprised of a specially tempered steel for maximum fatigue resistance. A patented winding of steel around the ball end of the plain strings reduces slippage, breakage and stays in tune better than conventional plain strings. Skinny Top Heavy Bottom Slinky Strings are the perfect hybrid set for those who like thick bottom strings without sacrificing the ability to solo on smaller strings. Gauges .010 .013 .017 .030 .042 .052. Part number 2915.