Last up to 3X longer - Amazing Tone - Effortless Feel - High Output - Great Sustain Cryogenically treated to enhance tone and feel while creating a longer lasting and more durable string. The cryogenic process removes transient material that produces harsh highs and muddy lows that kill the sound and life of your string. Made of 8% nickel-plated steel outer wrap on tinned Mandolin wire hex-core, Blue Steel strings have been bestsellers worldwide for over 30 years and are used by the best musicians everywhere. Once you try Blue Steel strings you’ll be hooked. They feel great, ring true, are durable and long-lasting with harmonics you won't find in any other string.