The superior concert string played by the great masters Augustine classical strings are designed to give you endless possibilities that will best suit your particular needs. The best way for you to decide which of our strings sets will sound best on your guitar is simple: try them and let your ears be the judge. Match one bass and one trebles set. The Imperial strings offer crystal nylon trebles that offer brilliant, bell-like tone. Mde in the USA. Imperial red strings include high tension trebles as well as medium tension basses and features: · E1 - .0287 inch. - 0.73mm · B2 - .0327 inch. - 0.83mm · G3 - .0406 inch. - 1.03mm · D4 - .0295 inch. - 0.75mm · A5 - .035 inch. - 0.89mm · E6 - .0425 inch. - 1.08mm.