What is "gas-pak"

Gas-pak is a method used in the production of an anaerobic environment. It is used to culture bacteria which die or fail to grow in presence of oxygen ( anaerobes).

These are commercially available, disposable sachets containing a dry powder or pellets, which, when mixed with water and kept in an appropriately sized airtight jar, produce an atmosphere free of elemental oxygen gas (O). They are used to produce an anaerobic culture in microbiology. It is a much simpler technique than the McIntosh and Filde's anaerobic jar where one needs to pump gases in and out.