This is a set of 6 chalks for graffiti, suitable for use on asphalt and other surfaces. Colors include white, yellow, blue, green, orange, and pink. Some have been used slightly, but they are still in near-new condition. Your children can enjoy graffiti to their heart's content. It can be washed away with water, so it's safe. The size is approximately 2 cm in diameter and 9 cm in length, larger than blackboard chalk.