Personalized 50 Is Just A Number T-Shirt. Happy 50th birthday! 50 is just a number. A BIG number! Fifty years is a long time, you know. 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.