Willson 551TAW Bb/F/Gb-Bass Trombone, Bb/F/Gb- Bass Trombone, Features an F-attachment and an Gb-attachment, Open-wrap construction, Rotax valves, Bore: 14.30 mm, Bell diameter: 265 mm, Gold brass bell, Nickel-silver outer slide, Chrome-plated inner slide, Slide can be removed, Newly designed slide stop, Clear lacquer finish, Includes a mouthpiece