Material: steel, with rustproof coating for durable use; Length: each guitar string is approx. 90 cm/ 35.4 inchPackage includes: 2 sets of acoustic guitar strings, each set has 6 strings in 6 different diameters; Good as spares in your bagString diameters: 1: 0.2 mm/ 0.007 inch; 2: 0.3 mm/ 0.01 inch; 3: 0.6 mm/ 0.02 inch; 4: 0.7 mm/ 0.027 inch; 5: 1 mm/ 0.039 inch; 6: 1.2 mm/ 0.047 inchColor: 1 set of guitar strings is multicolor (colors have blue, green, rose red, brass and silver); Another set is yellow (colors have yellow and silver)Suit for: colored guitar strings are helpful for the guitar beginners to remember and practice; Also fits for guitarist to make their acoustic guitar look beautiful and awesome