These replacement strings are all-nylon and their design is inspired and guided by the virtuosity of ukulele artist Jake Shimabukuro. This regular set for tenor ukulele is made from select Pro Arte' classical guitar string gauges. All D'Addario Pro Arte' strings are sorted by a sophisticated computer-controlled laser machine which performs diameter/tension measurements and quality checks ensuring that each ukulele string set is well-matched true-sounding and precisely intonated.