Dixon Lumber Crayons last up to 10 times longer than ordinary molded wax crayons. The extruded wax is fade-proof, water-proof, and smear-proof, and these crayons won’t melt in direct sunlight. They work well on wood, metal, concrete and most other surfaces. Hex shaped and each stick measures 4-1/2 x 1/2 inches. Graphite black. PMA Certified Non-toxic.