Fermentaholics Silicone Fermentation Stretch Lids - Waterless One Way Airlock Cap Fits All Wide Mouth Mason Jars - PATENTED Design - With One Lid Turn Any Mason Jar into a Vegetable Fermenter (1)

These rubber jar covers work really well at keeping dust and bacteria out while letting gasses and fluids out during the fermentation process. They take a little stretching in your hand first but after they’ve relaxes a bit, they fit and seal quite well over most wide mouth jars! Very easy to use and I’ve used one multiple times and it’s still good to use again!

Very easy to use. They make fermentation projects fun and easy to maintain. I plan to order more next season

Work great

Used for one batch. They were easy to wash before I used them. No problem stretching over a standard wide-mouth canning jar. I used 1 quart jars. They feel thin to stretch over something that's pretty big but didn't seem near tearing. Most guys are familiar with this experience LOL. I haven't tried a wider-mouthed jar like some other reviewers posted. They sealed well. I used a glass weight to hold the vegetables under the brine. The pickles produced are good. Try eating pickles with fresh hot rice if you haven't before.

I bought these a while back as a backup. I normally use the hard lids with the air locks ( highly recommend ). They were all in use so I decided to try one of theses, what a joke. I could’ve used parchment paper and a rubber band and got better results. They’re so thin and flimsy. The air lock is pointless. And when I went to check after just a few days, the inside of the lid was covered in black mold. I’ve been fermenting for years, never have I experienced this.

Seams kinda flimsy. Just put one on my Fire Cider and will see how it does. I will update as the fermentation process goes.

Only reason I gave it 4 instead of 5 stars for “leakproof” is I didn’t leave enough headspace in my jar and it bubbled up through the vent hole….my fault really!

Good product