Personalized Retro Rainbow World's Best Grandma T-Shirt. Give the gift of laughter and love with this adorable design that perfectly captures the essence of being a grandma. It's a great way to remind her how special she is to the family. So, whether she's a granny, mom, or just the world's best grandma, this apparel is a must-have for her wardrobe! 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.