Our plastic autoclavable wide mouth mason jar lids are built to be functional and affordable. Designed specifically for liquid culture cultivation, they feature a hydrophobic PTFE filter which can be held upside down and not leak. Our lids feature super heavy duty medical grade self-healing injection ports, and we seal each hole with high temperature silicon. Each lid comes with a reusable silicon gasket ring for an airtight seal. This type of lid must be left a 1/4 turn open when pressure cooking, and fully tightened when cooled. 1/2" heavy duty self-healing injection port wide mouth polypropylene plastic autoclavable lid sealed using high temp red RTV gasket silicon .45um PTFE air-exchange filter silicon gasket ring for an airtight seal PLEASE NOTE: If you are looking for a higher quality lid that will last much longer, checkout our new stainless steel metal ProLids here: https://www.etsy.com/listing/947880618/liquid-culture-prolid-stainless-steel