Unicorn Bags 5 lb Mushroom Substrate Bag 5 Micron (Pack Of 100)Measuring 8x5x19" and with a 5. 0 micron filter, these bags are able to hold 5 7lbs of your favorite substrate. These bags are fully autoclavable and have the highest gas exchange of all our bags. These are the only bags with filters large enough to preseal, and is effective against most contaminants, but can still be subject to attacks from smaller microbes such as bacteria, penicillium, and certain black molds.