Personalized Musical Triangle Youth Long Sleeve T-Shirt. The musical triangle disappear in it's complexity text with the image of a triangle is a humorous play on the Bermuda triangle and a funny gift design for percussionists, music teachers and students in orchestra and concert band. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)