The Large 4'' High Magnetic Alphabets are great for ages 3+, adding another dimension to endless spelling fun. Made of 100% natural rubber foam and not synthetic rubber. It is colored with child-safe, non-toxic paints sourced mainly from the USA. Natural rubber is the sap of the tree which is bio-degradable and renewable. Not only is natural rubber flexible and durable, it is also anti-microbial, dust mite resistant, mildew resistant, hypo-allergenic and flame retardant. While other companies might use fillers in foam, ranging from China clay to silica, Rubbabu does not. Its foam is pure, and therefore stronger.