It is made from stone absorbent ceramic with a natural cork base. The round coaster’s bottom layer is absorbent ceramic stoneware. The coasters for coffee table are 4 inches in diameter and 0.27 inch in thickness. Perfect size to fit most types of cups, such as tumblers, mugs, coffee mugs, wine glasses, sports bottles, tall glasses, etc. Cleaning your new absorbent coasters is just as easy as using them. Simply rinse the drink coasters in water, and brush it to clean. Dry it in the wind or sunshine. Orders of 1000 pieces or greater are eligible for sea shipping. 100% guarantee for quality.