Silicone Stopper, 4 PCS Airlock Stopper, Carboy Airlock Stopper with 8mm Hole, Silicone Plugs for Homebrewing Beer/Kombucha (#3)

As described

Works great, exactly as expected. I use it for a 1 1/2 inch tri clamp opening on a conical fermenter. I wanted silicone so that I could make another hole for a temperature probe housing. Much easier to cut those holes in silicone than the rubber stoppers

The stopper has the outer mold line of a #10 stopper, so it fits in the hole in my fermenter. However, the hole that is drilled out in the middle of the stopper is WAY too small for a standard air lock. I didn't give it lower than 4 stars since the ad says it's an 8mm hole. I just assumed they knew what they were doing--not so. Not sure what they drilled the hole for, but it's not for a standard air lock. I can force it in, but it will eventually break the air lock, just a matter of time. My other stoppers and grommets have 9.25 and 10 mm holes respectively.

Much better fit and grip for my carboy. No funky rubber smell.

As described, clean margins with no mold flashings, correct size.Silicone is just SUCH a superior material than standard rubber that if you have any doubts about spending a little more- don't worry. These things last forever without degradation such as stiffening, drying, or cracking. We even use silicone plugs at work, where they are exposed to hot lye, nitric/sulfuric/ferric, sulfuric with 12,000 volts DC current, more nitric, and then eventually near-boiling nickel acetate... and they don't break down except for abrasion by sharp metal, even with years of use!You can be confident that a bit of fermenter juice of your flavor of the week won't damage them a bit!The only thing that wrecks the surface of silicone over time is exposure to greases but I suspect most of us are planning to brew with them so no worries.

What I like about these silicone stoppers is that they fit the gallon jug. I had purchased "Amazon recommended " ones that claimed to be universal but they were too big for the carboy I was using. For reference, I am using one of these silicone bungs currently in a gallon glass carboy from Sprouts that had Apple juice in it. I had to fiddle with it a bit as it wanted to slowly slide up but a dry contact between the glass and silicone helped along with tightly wrapping plastic wrap to insure it would not move as pressure builds.It started bubbling within a couple hours of starting the mead. This silicone bung is constructed better than the hard plastic bungs that Amazon recommended.

Okay first off using in a 1 gallon jug, both need to be dry or it will slide out. The size is a bit small, I can stuff it almost flush in the top. It would be nice if when seated tight and snug (if there were slight carbonation won't back out) if there were 3/8's or 10mm left sticking out, to grip and remove it. Hence the 4 outta 5 Stars for design. Seller was fine. However these do plug the hole and do the job.

I'm very happy with these. I am not using them for their intended purpose, but they are working very well for what I'm using them for. These separate my Audio/Video equipment that are stacked. They provide space for heat dissipation. Plus the rubber helps keep everything in place because of the friction. The white mostly matches my Xbox One in color, but they are not opaque, so they are lighter in color. That's okay though becuase they look a lot better than the wood blocks I was using before.