Material: Black walnut, hardwood. The surface has been polished. Protected by varnish.Size: The 3.6 inch size holds the bottom of most cups perfectly. The thickness is 0.27 inches.Unique: Each coaster has its own unique texture, which makes the coaster even more special. In particular, it gives this coaster more purpose, and it makes a great gift for housewarming, hostess, birthday, holiday and so on.(Tips: If you have a solid wooden table. Trust me, this coaster will surprise you.)Easy to clean: Just rinse and dry. Just like you wash your hands.Lifetime Guarantee: Your purchase is protected, if you are not satisfied, we will provide a 100% full refund, please feel free to contact us. what are you waiting for