【Product Overview】 DR's BLACK BEAUTIES feature a special coating. This coating provides sound quality equal to or better than uncoated strings, and has received high praise from players. 【Features】 - K3 coating allows for longer string life than standard strings, without sacrificing sound quality. - Players report improved volume and clarity. Thank you for viewing. This is a new set, but only for a 5-string bass. The gauge is .125.