These chalks can be safely used by us. The cleverly designed brings us a comfortable using experience. The included chalk holder can prevent the chalk from cracking, effectively improving the use rate of chalk and reducing waste.These chalks are widely used in school, classroom, kindergarten, office and home, and so on. Features -Color:Assorted Color -Material:Gypsum -Size:7.50X1.00X1.00cm/2.95X0.39X0.39in -Size:11.00X5.50X3.00cm/4.32X2.16X1.18in -Size:9.50X1.80X1.80cm/3.73X0.71X0.71in -Note: Random Color of the Accessory - This colored chalk set is less likely to leave residue or stains on clothing or other surfaces. - Abundant amount chalks, enough for your spare and replacement, keep a long time use. - Dustless chalk is easy to write with and produces clear, vibrant lines on a chalkboard or other writing surface. - These chalks are comfortable to grasp and smooth to write. Vibrant colors, suitable for long-term use. - This colored chalk is great for use on blackboards, whiteboards, and other non-porous surfaces. Package list: 2 x boxes of Dustless Chalks 2 x Chalk Holders 1 x Eraser