Sealing film is a thin, transparent sheet made from materials such as polyethylene or polyester, which is used to cover laboratory vessels such as microplates, PCR plates, and cell culture dishes. The primary function of sealing films is to prevent contamination of the contents of the vessel by microbes, dust, or other particles. Sealing films come in various shapes and sizes to fit specific types of vessels, and can be self-adhesive or heat-sealable, depending on the application. Self-adhesive films are often used for short-term storage or transport, while heat-sealable films are used for longer-term storage or for experiments that require elevated temperatures. Sealing films can also have additional features, such as air-permeability or gas-tightness, to control the oxygen or carbon dioxide levels in the vessel.