Large Mushroom Grow Bag
[0.5 µm Micron Filter]
Unicorn Bag Type 14A

These bags are amazing, they're perfect for both bulk amounts of spawn and even using them to colonize and fruit sawdust blocks. In my personal experience sealing them before sterilizing them causes the bags to swell up inside the pressure cooker so I recommend using scotch tape to securely tape down the bags regardless of weather or not your using some tyvek filter.