CHALK IT UP. Each standard chalkSize measures 3 1/4" long by 3/8" inch in diameter. Marks smooth and erase easily from black board or chalk boards. SAFE & NON TOXIC. Non-toxic, smooth & clean writing. Suitable for all ages can enjoy create artistic and drawings activity. MULTIPURPOSE. Can be used on multiple surfaces like blackboard, chalkboard, craft papers, and paper bags. Low dust special formula create a dustless drawing experience. Safe for use indoor. BRIGHT SHADES.. Visible on dark or colored surfaces. Create big, colorful murals or write large handwritten messages in vivid shades. HOURS OF FUN. Great for school, classroom, cafe, office, home, daycare, summer camps. Ideal for children, toddler, teacher, teens, and adults.