Corelli CO-380-M double bass string set 4/4-3/4, medium, consists of CO-381-M, CO-382-M, CO-383-M and CO-384-MCorelli CO 380 M double bass string set 4 4 3 4, medium, consists of CO 381 M, CO 382 M, CO 383 M and CO 384 M Corelli's Nickel Soliste Series and Nickel Orchestre strings combine tradition and innovation. They present the same high acoustic qualities and benefit from the same innovations as the Tungstne Series 370 and 360. As a result they offer real advantages in comparison with other existing traditional strings.