Ethylene vinyl acetate (also known as EVA) is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene. It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other thermoplastics. Ethylene Vinyl Acetate (EVA) is widely accepted as safe for use in teethers. Ethylene Vinyl Acetate is a type of plastic that does not require a plasticizer and is bisphenol-a free, so it is considered to be a safer alternative material. Ethylene Vinyl Acetate is a durable, flexible, transparent copolymer plastic.