GHS Strings TC-GBXL Thin Core Boomers, Nickel-Plated Electric Guitar Strings, Extra Light (.009-.042). Thin Core Boomers are perfect for those who want to push the limits of speed and dexterity to the next level. With their slightly smaller core, these Boomers provide lightning fast action and faster speed runs as well as more precise arpeggios and musical bends.