All Pro-Arté treble strings are computer controlled by an X-Y laser microscope which performs diameter and tension measurements, ensuring true-sounding, precise trebles in every set. Pro-Arté basses are wound using silver-plated copper on a multi-filament nylon core for consistent and warm, yet projecting tone. Features Hard tension for increased resistance, volume and projection Laser controlled clear nylon treble strings for consistent, precise intonation Precision wound basses for warm, projecting tone and the utmost consistency Environmentally friendly, corrosion resistant packaging for strings that are always fresh All D'Addario strings are designed, engineered, and manufactured in the USA Specifications Tension: Hard Size: Full Scale End Type: Tie-End Coating: Uncoated Number Of Strings: 6 Set Type: Sets, Multipacks Monofilament Material: Nylon Wrap Material: Silver-Plated Copper