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. Ernie Ball 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. Super Slinkys are one of the most popular gauge combination preferences by guitar players.