CounterArt Petroglyph Design Round Absorbent Coasters in Wooden Holder, Set of 4 Set of 4 absorbent natural stoneware coasters in wooden display holder Coasters are natural stoneware with decorative transfer print- holder is made of durable rubberwood with a clear varnish finish Southwest petroglyphs To remove coaster stains, soak coaster in 1 part household bleach and 3 parts water until stain lifts, then rinse and air dry