KQXS-1260, C# X-Xxtra Heavy NPS Electric Gauge .012, .016, .022P, .038, .048, .060. Feeling a heavy gauge string under your fingertips gives you extra power while cutting through with an unmistakable growl and chunk. These tonal flavors are a necessity for hard hitting, drop tuned riffs and passion driven playing. Sinister Strings are seasoned by a patented process between minus 320F and plus 350F for 24-36 hours. The repetitive Hot/Cold Tempering process causes the metal to expand and contract, which reduces the microcracks that cause tonal loss and premature breakage. The result is a Long-Life Guitar String.