Our Start / Start+ 2.5mm Eco-filaments are low-heat, BPA-free and non-toxic strands that are eco-friendly and completely safe for kids. Safe to Doodle on almost any surface, the material can be easily removed, though will adhere firmly to some clear plastics. Each strand of material extrudes up to 6 times the original length. One six inch strand can produce over 35 inches of Doodles.