Baize is the usually green or blue felt-like covering on a pool table, and can also appear on high-end card tables, other types of gaming tables, and in parts of a piano. It is most often fashioned out of wool or a type of wool-blend. Baize also covers the four edges on the table, also known as "cushions". Baize can vary in thickness and furriness, depending on its purpose. On billiard or pool tables, it is also crucial to have the baize be as tight as possible, as to not interfere with the movement of the pool balls. The baize can also become dirty with chalk or other substances (such as beer, other types of alcohol, vomit, potato chips, or soda), and must be brushed regularly with the table brush, which comes with most pool tables.