DyeTrans? Coaster, Square Black Rubber with White printable top, 3.5″ Square x .22″ (5.5mm). Not only are these coasters great for protecting furniture, but they are also the perfect way to add a little personalization to any living room or office space. Looks fabulous when imprinted, personalized with photos or pictures. Polyester with open cell black rubber backing. Make matching mugs too!