Features: All TWEE producs are handmade. TWEE’s chalk is meant to be used on surfaces with grit. This includes sidewalks, asphalt, concrete, slate, etc. TWEE chalk is more dense than chalk used on chalkboards, making it stronger and less likely to break in use and in transit. Complies with ASTMD-4236 standards. Suggested age: 3+ TWEE products are non-toxic – even the glitter is biodegradable and eco-friendly! TWEE packaging is fully biodegradable and recyclable (the clear windows are made of plant based film instead of petroleum based plastic!).