Key Material: Copper, Key System: Curved Closed Cell E Key Surface Treatment: Nickel-plated Cupronickel, Number of Sound Holes: 16, Body Material: Cupronickel. This instrument is designed for maximum sound quality with its copper material and nickel-plated cupronickel key system, as well as the 16 sound holes for a balanced tone. Enjoy professional-level playing with a crisp, clear sound.