"Bio Chalk" is the first multi-functional product in Korea, that doesn&＃39;t create dust powders. "Bio Chalk" could be used everywhere including a blackboard, paper, glass, teacher´s desk and so on. - As being made of natural elements, it is not harmful to a human body. - As superior writing feeling, it could be used for a long time.If you need any further questions or information, please do not hesitate to contact us, we will send you information you need.