Carboy Bung (Silicone) - Breathable

Carboy Bung (Silicone) - Breathable

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This high quality Silicone Stopper gives a great airtight seal while still allowing gasses to escape. 
Fits 3,5,6 & 6.5 Gallon glass carboys and 500ml flasks. This breathable Silicone Carboy Stopper acts as both a solid stopper and an airlock. The unique design allows CO2 pressure to escape but keeps oxygen and airborne contamination out. Beer makers love using it during the ferment because it creates a vacuum when the wort cools, instead of pulling water in from your traditional airlock. The airtight seal is great for extended lager fermentations when CO2 production is still present but only very slightly. 
Measures 1 1/2" wide at the top and 1 1/8" at the bottom.
You may also want to check out our Premium Breathable Silicone Carboy Hood.
Item # FE479
Shipping Eligible for Free Shipping Program
Availability California - In Stock
Pennsylvania - In Stock
Weight 0.10LBS
Community Q&A

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Why did you choose this?
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I age my beer a long time.
Geovanne T on Oct 1, 2019
we have some and love the
Mary C on Aug 28, 2019
I age my beer a long time.
Geovanne T on Oct 1, 2019
might need it
Kenneth W on Aug 28, 2019
we have some and love the
Mary C on Aug 28, 2019
Updating equipment
Roger Ladd on Aug 28, 2019
Easier than 2 part stopper
Pamela S on Jul 7, 2019
Recommended by more advanced winemakers
Susan P on May 29, 2019
Wanted to buy them for a while. Got them now to get free shipping.
Mihai Bordea on Apr 18, 2019
more compact storage during fermentation
John E S on Feb 27, 2019
Simple lock
Todd Hilsmeier on Feb 11, 2019
Josh F on Feb 5, 2019
worth the money your the best.
john morton on Jan 11, 2019
Looks like a nice alternative to liquid filled airlocks.
Brad B on Dec 31, 2018
Works great for secondary fermentations
Andrew P on Nov 27, 2018
I have several, they work well for me
Brewdude on Oct 24, 2018
just giving it a try
Jerome J Ferguson on Oct 15, 2018
No need to top-up airlock during bulk ageing
Valued C on Sep 24, 2018
need it.
Mark H on Sep 24, 2018
Best one
Roger H on Sep 19, 2018
Much better than bubbler.
Edward G on Sep 11, 2018
just wanted some caps for my carboys
Levi A G on Sep 10, 2018
Tried 3 last year and am converting over. No more topping maintenance
William H on Sep 5, 2018
they work
steve m on Aug 28, 2018
Trying for first time
Robert A on Aug 21, 2018
Great alternative to an airlock, don't have room in my fermentation chamber for a full airlock.
Dalton R on Jun 26, 2018
have more carboys now
Heart Wood C on Jun 6, 2018
Perfect for a 500ml starter
Art Blackwood on May 15, 2018
Matthew T on Apr 17, 2018
Looks like a good answer vs. refilling fermentation locks for long holds
William H on Apr 3, 2018
Want to try ditching the bubbler
Alex Fenocchi on Mar 20, 2018
Have one and love it. I use plastic carboys which can suck in water from a regular airlock when flexed when moving.
Karyl N on Jan 25, 2018
I want to fill holes in things
might need it
Kenneth W on Aug 28, 2019
Updating equipment
Roger Ladd on Aug 28, 2019
Will this fit the one gallon glass jars?
Keith Smith on Sep 3, 2018
BEST ANSWER: No, absolutely not. I just tried it several times. You can force it in, but it always pops out. Don’t know why they wouldn’t make a #5 breathable. Maybe reach out to the company.

4.7 / 5.0
16 Reviews
5 Stars
4 Stars
3 Stars
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1 Star
Great stoppers for bulk aging. Recommended.
September 30, 2019
6 months ago
Nifty Little Alternative
These are really nice to use after primary attenuation is complete. My only worry is creating to much negative pressure differential in a glass carboy when cold crashing. Might the carboy implode? Either way, that is no fault of the product. LOVE IT!!!
August 19, 2019
3 months ago
Really like these
I really like these. I use them after all fermentation is complete. They are cleaner and more maintenance-free than bubbler airlocks at that point in a wine's life. I've never had an issue with a carboy of wine upon which I used the silicone stopper.
January 31, 2019
1 year ago
A great product
These things are great for use after fermentation is completed, when watching a visible air lock bubble is not longer of any value. They stay seated very well. I plan on buying several more soon.
January 9, 2019
1 year ago
Good replacement for a standard airlock
I love these stoppers - use with my Anvil brew bucket since I can’t fit an airlock in the fermentation chamber. Works as well as a traditional airlock in my opinion - let’s the CO2 out, doesn’t let any bugs in.
July 8, 2018
1 year ago
Way better than maintain fermentation locks
I stage my wines for a bit in carboys and this stopper is a nice no maintenance answer vs. topping up carboys. It's not unusual for me to have 10 or more carboys in-process so this is a time saver for me, and piece of mind.
April 7, 2018
1 year ago
These might work great but you have to buy the correct size. These do not fit my carboys. If you have plastic carboys you need a size 10. I have 5 of the wrong size, but can use them on gallon jugs.
February 19, 2018
1 year ago
Effective & easy to use
Have switched over (from rubber type with a trap) to silicone with the flap. Very easy to clean and use. Don't need to use a water/alcohol filled trap. Stays put and easy to remove. Works as expected.
February 17, 2018
1 year ago
Great when stacking carboy carriers 3 high and 3 deep...
January 27, 2018
1 year ago
great alternative to a typical airlock
These are a great alternative. No need to fill--or top up--with water. They also prevent any backflow of air (such as when cold stabilizing). One caution: when wet they are quite slippery and can pop up. It helps to give them a twist as you're inserting them.
January 24, 2018
1 year ago