Biomed Solutions Mushroom Grow Bag Cap and Ring for Cultivating Sealing Cotton Filter Cover 40mm(Pack of 9)

You can reinforce the filter with another layer of porous tape + loosely placed aluminum foil (for breathing), but they do the job of keeping the contaminants out while providing safe and easy access for inoculation.

May be my fault but I couldn’t get the cap on the collar. It was like the bag was interfering with it snapping in place.

The sleeves work really well. Some people have said they don't secure well at all but I don't think they are actually clicking the 2 pieces closed. They are very difficult to pry apart once you close them. Only downside is the cheap foam filter on top. I added some micropore tape on top of the filter and it works fine.

I haven’t yet got to PC these….but I will say that they are nice and thick…….they feel super solid. Exactly what I wanted for the tek I’d like to try.

I wasn't really impressed with the quality of this product. I'm fairly new to mushroom cultivation so I was really excited to try these rings out but when I got them they were subpar in my opinion. They are super small and flimsy I'm not even sure what the filter is made out of and there were no instructions whatsoever. Save your money for some better options that are out there.