Fluorocarbon trebles for brightest tone of all La Bella trebles Silver-Plated wound basses produce exceptional memory for pitch and consistent sound production Medium Tension String Gauges: Fluorocarbon Trebles: .024 .027 .033; Silver-Plated Wound Basses: .0285 .035 .0415 Made in the USA with American Wire Packaged using MAP Technology (Modified Atmosphere Packaging) to prevent tarnishing and ensure freshness