Super Mario Brothers Custom Rectangle Pillowcase Covers Standard Size 20"x30" One Side Twin Mario Pillowcase Standard pillowcase is roomy in size (20'' x 30''). Best choice as a gift. Comfortable and 100% Brand New Made of 50% cotton, 50% polyester! The pattern image is only on the front side. Custom Design Your Own Personalized Rectangle Pillow. Having this soft custom pillowcase will add both comfort and style to your home.