Symphony, .547" (13.89mm) bore with patented CL2000 F rotor system, open wrap, .562" (14.27mm) bore through F attachment, 8-1/2" (216mm) thin rose brass bell & outer slide, lacquer finish, C.G. Conn mouthpiece, 7521L woodshell case. The CL2000 rotor system provides 40% faster action & virtually eliminates any response difference between the F attachment & straight trombone sides.