This "no-dust" chalk, which can be used on all types of chalkboards, is made of 98% calcium carbonate. Non-toxic, conforms to the ASTM D-4236 safety standards, and has the Art & Craft Materials Institute AP seal of approval. 3/8" diameter x 3 3/16" long. Box of 12 sticks. Case of 144 boxes. Yellow. Eco category: less toxic. Ground shipping included in continental US!