These modified lids are perfect for mushroom liquid culture because the filter disc is waterproof. This allows the grower to transport jars to and from buildings without the worry of liquid splashing up and hitting the filter causing contamination.
The lids can be reused a few times before being replaced. They hold up well in the pressure cooker. I also use another layer of protection by adding a coffee filter to the lids after inoculation to prevent dust from settling on the jar lids overtime.