It seems there is a mfg defect with this product. The bags at Costco overwhelmingly had a small tear in the back. This did not appear to be an engineered vent hole. I wrote this company but haven't got a response in five days so I am posting here. On the larger bags from Costco, be aware that they may not be fresh due to this production error. I checked this hole against other smaller bags at Superstore and no holes existed. Their own website says to keep the bag tightly sealed, which is impossible when it comes with holes in it. Some bags had two tear marks in the same spot. Check your product, back side top left as in my photo.