These heavy-duty filter discs are designed for gallon-sized spawn jars with a 125 mm opening. This size filter is also popular with mycologists that make their own custom spawn lids, as it can easily be cut down into many smaller filters that can be used on custom lids. These filters allow for gas exchange while providing 99.97% efficiency filtration down to 0.3 microns. Autoclavable. They are 100% reusable and the best filter available for spawn production or canning jar cultivation.
To use this filter, simply fit it snugly under the jar lid, or place it on top of the jar lid and secure it with the jar band.