This Mouthpiece Shank Repair Tool Set is comprised of a mandrel tool and a sleeve specific for (French) horn mouthpieces. The mandrel tool is made of 303 Stainless Steel and is tapered to fit mouthpieces for trumpet, cornet, flugelhorn, horn, trombone (small, large & bass), baritone, euphonium (small or large), and tuba. The kit includes a Mouthpiece Shank Repair Sleeve. The sleeve is used to prevent your mouthpiece shank from becoming oblong or stretched during the repair. The mandrel tip has been redesigned to fit the smaller horns and the occasional "fold over" from dropping.