One dozen reusable synthetic filter discs, wide mouth 90mm diameter.
Drill a small .25in - .5in hole in your plastic jar lid or jar lid dome and place a filter under it, securing it to the jar with the lid. The hole size can vary depending on how much air exchange you want for your spawn... the larger the hole, the more air will be exchanged. Larger holes may lead to excessive drying of your grain spawn.
Great for speeding along your spawn runs, a useful accessory for any mushroom spawn creation.