.459″ (11.66mm) ML bore, 4-13/16″ (122.24mm) diameter one-piece hand-hammered yellow brass bell with side seam, #25 mouthpipe, brass inner and nickel silver outer slide tubes, two piece nickel/brass valve casings, Monel pistons, 1st slide thumb saddle, brass and plastic valve guides, deluxe engraving, and deluxe case