DR Strings Tite-Fit round-wound nickel-plated electric guitar strings are designed to be a great all-around string. Based upon a round core, the construction techniques for the Tite-Fit electrics are very old. However, the core wire and wrap wire in DR's are the latest, most advanced and expensive metals available. For flexibility, for tone, for long life; for rock, blues, heavy metal, jazz.. Tite-Fits are an incredible all-around string.