Personalized Retro Santa Believe Long Sleeve T-Shirt. Retro Christmas Long Sleeve T-Shirt - White with an old fashioned, vintage Santa Claus, snow flakes. He says I BELIEVE! Perfect for kids and kids at heart. Pre-shrunk 100% cotton 6.1 ounce long sleeve t-shirt. Double-needle stitched neckline and sleeves. Quarter turned. Shoulder-to-shoulder taping. Adult: S, M, L, XL, 2XL, 3XL