GHS Strings GBM Guitar Boomers, Nickel-Plated Electric Guitar Strings, Medium (.011-.050) Model: GBM Featuring the air-tight Fresh Pack & NitroPack singles, guaranteed fresh from the factory! Roundwound Nickel-Plated Steel on a Hex Core Offers a brilliant tone and powerful attack, THE POWER STRING. Medium Gauge: 011-015-018-026-036-050