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Flip-Off® Seals 

A Flip-Off® seal is your drug product’s first line of protection; it helps keep contamination from getting into the vial and seals the parenteral package. Further, the seal helps to protect the injection site on the vial stopper. Recommended seals consist of an aluminum shell and a plastic Flip-Off® button. When selecting a seal to complete your drug package, you should consider the following attributes:

  • Quality of construction
  • Ease of use
  • Tamper evident properties
  • Sterilization compatibility
  • Drug product storage and shipping conditions

In the early stages of component selection, a critical factor is ensuring you are able to maintain container closure integrity over the shelf life of your drug product.

The Flip-Off® seal protects
the injection site of the stopper.
Flip-Off® seals are easy to use
and provide evidence of tampering.

Major factors that directly affect container closure integrity are the dimensional “stack height” of the vial, rubber closure, seal skirt length and the method of crimping the seal onto the vial container. There are many variables that can affect overall stack height:

  • Vial:
    • Method of manufacture
    • Crown dimensions
      • Outside diameter, crown height and radii
  • Rubber closure:
    • Flange thickness
    • Durometer (the degree of hardness and softness of the material)
    • Finish or films and coatings
  • Seal:
    • Aluminum skirt length
    • Overall height
    • Inside diameter

Determining stack height to select the proper size seal can be a challenge if you are unfamiliar with the construction, variability and make up of container components. A West Technical Customer Support Representative can guide you through this process by recommending the proper size and type of components to meet your needs. Click here to contact West by phone or by email.

The Flip-Off® seal is designed with the end user in mind, making it easy to remove the seal from the vial with one hand. Flip-Off® seals provide evidence of tampering and the button cannot be reassembled onto the seal once it has been removed.

Selecting the correct vial, stopper and seal combination helps assure container closure integrity.

West offers a variety of Flip-Off® seals to meet your selected method of sterilization and drug product storage and shipping conditions. Functional and dimensional properties remain constant, with only the base resin of the Flip-Off® plastic button changing.

  • Flip-Off® seal with a standard homopolymer polypropylene plastic button – autoclavable

  • Flip-Off® seal with a copolymer resin plastic button – cold temperature applications for drug products that are stored frozen, refrigerated or packaged product that is shipped on dry ice (-80 °C)

  • Flip-Off® seal with a gamma stable resin plastic button – compatible with high energy radiation


Flip-Off® seals can be molded from resins suitable for various forms of sterilization and storage conditions.

West’s Flip-Off® seals are constructed from pharmaceutical grade materials that meet Coalition of North Eastern Governors (CONEG) regulations and current Food and Drug Administration (FDA) recommendations. All manufacturing processes operate in accordance with applicable Current Good Manufacturing Practices (CGMPs).

Flip-Off® is a registered trademark of West Pharmaceutical Services, Inc.

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