BBb, all brass, .687" (17.45mm) bore, 26" (660mm) bell, silver plate finish, 24AW mouthpiece. This all-brass sousaphone is renowned for its wonderful tone quality, projection and volume. Built with oversized braces and extra large brass caps and guards for extra protection and durability. 24.2 lbs., 7560L - ABS plastic hardshell case with wheels. Full warranty.