Michael Rath R1 Tenor M, Bb Tenor Trombone, Dual bore: Ø 0.5""/ 0.51"" (12.70 mm/12.95 mm), Bell size: Ø 7- 1/2""(190.50 mm), Bell made of yellow brass, Nickel silver outer slides, Tuning slide made of yellow brass, Gooseneck made of yellow brass, Lead pipe: #1, Without mouthpiece and case