Ernie Ball M-Steel Electric Guitar Strings are made of a patented Super Cobalt alloy wrapped around a Maraging steel hex core wire, producing a richer and fuller tone with a powerful low-end response. M-Steel plain electric guitar strings are comprised of a specially tempered steel for maximum fatigue resistance. The electric plain strings also utilize a patented winding of steel around the ball end that reduces slippage, breakage and stays in tune better than conventional plain strings.