Darco strings are produced by Martin and have the consistency, quality and tone you?d expected from this legendary brand, but at two thirds the price. Darco bass strings are made of a compound nickel wire wrap around a tin plated, steel core promoting solid playability and stability. These premium nickel guitar strings are made to be robust and affordable, in a variety of gauges for different playing styles. Your reliable guitar string for gigs, studio or just everyday playing. String gauges: 45-65-80-100 Tension: 174.9