... toxic;no dust. 2,natural mineral without any chemical ingredients. 3,1pc slate pen equals 20pcs common chalk for using. Basic Information ... 28Features1,slate pen,the same function as traditional chalk.2,which is made of natural mineral without any chemical ingredients;no dust ... ,chalk board, whiteboard, writing & drawing boards,color clay,slate pen and so on. Our company takes quality as the lifeblood ...