Von York ® Cryogenic series Acoustic Guitar Brass Strings Kelvinite® Acoustic Guitar Brass Strings Lights Dimensional stability means stable pitch with relatively little stretching, so they stay in tune longer. 80/20 Bronze – Composed of 80% copper and 20% zinc, commonly referred to as brass, produces a warm crisp sound without any harsh overtones. Ideal for recording designed to give you excellent tone, clarity, and response. The world is yours with Kelvinite by your side.