For your consideration are these top of the line mushroom grow bags. These medium bags are 8" X 4.8" X 19" with gusseted sides! Medium grow bags with a high filter allows you use much more substrate then most other bags available on the market. Use these bags for bulk grows and get great results. The 5.0 micron filter patch allows for proper gas exchange but excludes water vapor so your spawn does not dehydrate. The filter also keeps contaminants out. We choose this filter size for its efficiency and because it allows the bag to be sealed before you sterilize. The material is polypropylene and is heat resistant up to 260F. Gas transmission is 1 in h2O. Medium bags are acceptable for spawn running and bulk substrates. You will need a 12" or larger impulse sealer to properly seal these bags, however you can get away with using paperclips, packing tape or a similar device. This side-gusseted breathable bag gives a sturdy stand-up bag after filling and a strong bottom seal. We manufacture it with equipment we designed and with proprietary additives, These bags are pliable at any temperature as well as after sterilization. The bag opening is designed for easy sealing and the bag's bottom seal can withstand agitation.