CounterArt Oliva Design Natural Sandstone Absorbent Coasters, Set of 4 Set of 4 absorbent sandstone coasters Coasters are cut from natural sandstone with decorative transfer print Beautiful, colorful design meets high functionality with this coaster set Cork backing protects surfaces from scratches To remove coaster stains, soak coaster in 1 part household bleach and 3 parts water until stain lifts, then rinse and air dry