NYLGUT, REGULAR TUNING - Key of C (GCEA, 4th to 1st, "bass to treb"). Strings are plain Nylgut. Nylgut is polymerized plastic with additives patented by Aquila. It has the closest sound to gut strings we have heard. Made in Italy. Gauge, 1st to 4th, about 0243, 0305, 0373, 0265 inches.