Yamaha YSL-354 Standard Series Key: Bb Bore: M: 12.7mm (0.500") Bell: Yellow-brass 204.4mm (8") Weight: Standard Outer slide: Nickel silver Inner slide: Nickel silver Finish: Gold lacquer Yamaha's Standard model tenor trombone features many of the qualities of our top pro models yet is available at a surprisingly affordable price. The response is quick the intonation accurate and the sound both rich and full. The outer slide is made of nickel silver on European models and is brass in other territories.