A core essential in every wardrobe, a simple black shirt can pair with anything. The SI Core Tee is a soft poly/cotton material with plenty of stretch, ribbed collar, and soft seam construction. Subtle Oakley SI logo on sleeve. A soft Poly/Cotton material with plenty of stretch, ribbed collar, and soft seam construction keep you in your comfort zone - while the large Oakley graphic gives you a confident look that lasts.