Vinyl cord. Made of silicone rubber. Antimicrobial protection that will not wear or rub off. Made of silicone rubber for comfort; non-toxic, and non-irritating. Durable plugs that can be sterilized in boiling water or alcohol. Triple flange design provides a multi-surface sealing over a wide range of ear canal sizes. Earplugs can prevent water from entering the ear canal and protect ear membrane.