Autoclavable filter patch bags designed specifically for mushroom growing. The filter patch on the bag allows the mycelium to breathe, while keeping contaminants out.

These are great for making grain spawn, or sawdust blocks for fruiting. They can be autoclaved / pressure cooked to 15 PSI (121°C). They can be sealed closed with an impulse sealer (heat sealer) or can be closed at the top by twist and fold over the top and then cable tie. 

Small size: $1.50 each (holds approx 700g-1kg hydrated grain for spawn)
Medium size: $1.90 each (holds approx 1.5kg of substrate)
Large size: $2.30 each (holds approx 2.5kg substrate standard '5lb' production block)