Product description They are widely used by mushroom growers throughout the world. We use them for mushroom spawn incubation in our farm for a long time. Sealable and autoclavable, 3 mil polypropylene bags with micro porous filter patches that allow gas exchange but preclude the passage of contaminants, can be used for both mushroom growing and spawn .You can seal them with an impulse sealer, or just tie to seal them. Those bags are durable and can be reusable in most circumstances. Sealing method: Mushroom bags can be sealed with an impulse sealer, or just tie to seal. These bags are durable and can be reusable in most times. If there is a slight damage to the bag, there is a risk of bacterial infection. Water content of culture material: If the water content of the medium is too high, the ventilation will be affected, hyphae will grow slowly due to lack of oxygen, moisture will be deposited in the lower half of the cultivation bag, and the hypha length will not be able to go. Please refer to the following standards: 1. Grain food: ±42% moisture 2. Mushroom culture material: ±62% moisture please handle it carefully. 3.Suggested Sterilization Times at 15 PSI: 5 LBS Grain Bags---120 mins 5 LBS Sawdust Blocks---150 mins Specifications: 0.2 Micron Filter Extra Thick 3 Mil Bags Large Size 6" X 5" X 20" Breathable Window 2" X 2" LARGE SIZE, GREAT VALUE: 50 Pack of 6" X 5" X 20" Grow Bags Allow plenty of room for mushroom growing and spawn Substrate and fruiting. These side-gusseted breathable bags Stand up and hold strong. Please feel free to contact us if you have any questions. Thank you!