GHS Silk and Steel acoustic guitar strings are wound with silver-plated copper wire over a silk and steel core to yield a sweet, mellow tone with a soft feel. Silk & Steel strings are perfect for accompanying the singing voice. Gauges: 10-13-20-26-34-42 Factory Fresh The GHS strings you buy are as fresh as the day they were made. All GHS facilities are environmentally regulated to control temperatures and humidity. Sensitive raw materials and bulk products are further wrapped in protective bags for storage. Coiled strings are placed in string packets that, in independent laboratory tests, have proven to offer the optimum protection from humidity.