64Pcs 20mm Diameter Synthetic Filter disc Hydrophobic PTFE Membrane 0.3um Pore Size Strong Adhesive for Mushroom Cultivation

This is what you want on your grain jars... more air exchange = faster growth

Purchased these to modify some grow tubs. The smaller ones work best for my tubs. If using the larger patches, less is more. Tried using 4 of the larger patches and it allows too much gas exchange and it's hard to keep humidity.

Great for making your own home made spawn jars! They stayed on after sterilization!

I used these to filter some gas exchange ports in a high humidity environment and they are doing a great job. There is a noticeable amount of gas and humidity exchange in an a radius around each filter. The adhesive is strong and bonded well with plastic. There is a circle cutout on the throw away backing that is probably useful for sanitizing the “clean side” of the filter prior to application, otherwise I don’t know why they’d go through the trouble to cut holes in it.

I love these! Very easy to use, made it through the pressure cooker at least 3 times so far, and still look good as new. I have made at least 20 mushroom jars with no contamination. Will be a repeat consumer of these.

this is a good product after further investigation I discovered that all of the patches were there I initiated a return but would like to cancel that now thanks and sorry about the confusion

Worked great for my project.

Excellent