The fermenting lid is used to produce fermented vegetables. To produce safe and beneficial fermented vegetables, some fundamentals need to be adhered too: (i) carbon dioxide produced by the fermenting microbes must be released, to avoid the risk of the container exploding; (ii) oxygen must not enter the container as the production of lactobacilli bacteria will be impaired, as an anaerobic environment cannot be maintained; and (iii) vegetables are completely submerged in a saltwater brine to avoid spoilage. The fermenting lid allows carbon dioxide to escape the container, prevents oxygen from entering the container and keeps vegetables completely submerged in its brine. Refer to Fermenting Lid instructions for more information. The Fermenting Lid fits the 1.0litre and 2.0litre Super Screw Lid Jars.