Pacific Vial 20mm round bottom serum vial non-sterile stoppers are for serum vials with a 20mm outside rim-to-rim diameter. We also offer similar 20mm vial caps in white. Appropriate washing, rinsing and sterilization, if required, must be performed by the purchaser.
20mm round bottom serum bottle stoppers are made of chlorobutyl rubber. Manufactured in the USA.