Personalized Trombone Text Shamrock T-Shirt. A shamrock made from the word trombone and small shamrocks is a unique gift design for low brass musicians and music students and teachers on St. Patrick's Day and at Celtic festivals. Everyone loves our Custom T-Shirts! Wardrobe essential for looking good, 24/7. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar. Shoulder-to-shoulder taping. Double-needle stitched sleeves, bottom hem and front neck. Note: greys are a cotton/polyester blend.