These coasters are made from Medium Density Fibre Board (MDF), which is engineered using wood waste. Only about 65 to 70 percent of a tree can be used for solid lumber. MDF is made from the remaining wood waste which are combined with a resin and wax at high temperatures to create a strong, versatile fibreboard. Since 100% of the leftover wood can be used in making MDF, it is a very efficient use of our precious tree resources. Size: 3.5" * 3.5"