3 mil polypropylene bags with 0.2 microporous filter patches that allow gas exchange but preclude the passage of contaminants, can be used for both mushroom growing and spawn. They measure 8 x 5 x 19 inches, have a 2.1 x 2.1 inch 0.2 micron filter which allows for the passage of air but not unwanted contaminates. Reusable, can be sealed with an impulse sealer, taped or tied shut at the ends.
