NATURAL STONE - These black stone coasters are made of natural slate, each piece has unique texture, so each piece of coaster is unique. FOOT PADS - The bottom of the slate stone coasters has soft foot pads, which can not only avoid slipping but also can avoid friction between coaster and table, protect the table from scratching. SMOOTH EDGES - To protect your hands form hurt, we make the edge of slate drinks coasters smooth through carefully sanded, smooth edge also make the coaster look neat and beautiful. METAL HOLDER - You will get 12 pieces black slate coasters and this set comes with a metal holder, it is very convenient for organisation and storage. WORRY-FREE PURCHASE - If you have any dissatisfaction or feedback with slate round coasters after receiving the product, you can contact us. We are dedicated to providing you a satisfactory shopping satisfaction.