EVA is short for Ethylene Vinyl Acetate. It is a durable, flexible, transparent copolymer plastic.
Wikipedia describes the following uses for EVA:
EVA is typically used as a shock absorber in tennis shoes. It can be recognized in many crocs brand shoes and accesories, in the form of a foam called crocslite.
The foam is also commonly used as padding in equipment for various sports such as ski boots, hockey, boxing, and mixed martial arts.
EVA is used in biomedical engineering applications as a drug delivery device used within the body. While the EVA is not biodegradable within the body, it is quite inert and causes little or no reaction following implantation.