These chalkboard chalks are made of gypsum powder materials, safe, and durable. In addition, the gypsum chalk writes smoothly and comfortable to use. Using these chalks, you can make stunning masterpieces on most surfaces, such as blackboard and sidewalk. Features -Color:Yellow -Material:Gypsum powder -Size:10.30X2.50X2.50cm/4.05X0.98X0.98in - The chalk allows you to write smoothly, and easy to erase, can be used to painting on blackboard, sidewalk and so on. - This type of chalk is perfect for use in classrooms, offices, outdoor sidewalk and other places as needed. - The chalk is also great for use at home, suitable for kids, children, parents and teachers. - These chalks have a wide of application, and there are adequate quantity can easily meet your needs. - This chalk set is an excellent gift choice for kids who love to create eye-catching art and paintings. Package list: washable chalks