Personalized Assistant Coach Planets Best T-Shirt. Planet's Best Assistant Coach T-Shirt - White gift has earth globe logo and room to personalize for the world's best Assistant Coach. Everyone loves our Custom T-Shirts! 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.