FDA applies its device definition from the Federal Food, Drug, and Cosmetic Act: if the article is intended to diagnose, cure, treat, prevent, or mitigate disease, or to affect the structure or function of the body, it is a medical device. Rubber articles with purely hygienic or comfort functions (e.g., hot water bottles) typically fall outside device classification, while items like rubber catheter components or drug-contact closures are regulated as devices or drug-contact materials. Intended use labeling and marketing claims are the primary determinants.

Unhardened vulcanized rubber retains flexibility and elasticity after the vulcanization process, while hard rubber (ebonite) is vulcanized with a high sulfur content that renders it rigid and non-flexible. Articles of hard rubber — including waste and scrap — are classified under a separate SITC heading (62991). The physical flexibility test and sulfur content of the compound are the key technical differentiators for classification purposes.