Personalized Retro Rainbow World's Best Grandma T-Shirt. Give your grandma the recognition she deserves with this stylish and funny apparel. It's a perfect way to express your love and appreciation for her unique role in the family. Whether she's a nana, granny, or just the best grandma ever, this design is a delightful reminder that she truly is the world's best! 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.