EXCLUSIVE! The M is a mezzo notation, the U is a pair of beamed notes, the fancy-schmancy S is a segno, the I is a quarter-note rest, and the C is the symbol for common time. If you're a musician, you already knew all that. White sweatshirt is 50/50 cotton blend, T-shirt is preshrunk 100% cotton. Sizes S-3XL. Imported.