Martin M120 Silverplated Classical Acoustic Guitar Strings High Tension Plain End Gauges 28-32-40-30-35-43. Martin M120 Silverplated Classical Acoustic Guitar Strings feature plain ends. Their silverplated winding resists corrosion, has a longer life, is easier on the fingers, and delivers clear tone. Martin acoustic guitar strings are high-quality strings intended for daily use. Core and wrap wires must meet strict requirements to make the grade. Martin strings are wound to precise specifications to assure you the sound you seek from your guitar.