Excellent sound and longevity with a silky feel. 80/20 composition alloy for brilliance, clarity, and longevity of sound. The Bronze winding is ideally suited for making strings that have deep, rich basses and clear, bright trebles. Martin Strings are high-quality strings for daily use. Core and wrap wires must meet strict requirements to make the grade. Martin Strings are wound to precise specifications. M450 - 11-14-24-38