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Fermentology Carboy Caps are the perfect accessory for brewing homemade wine, beer, mead, kombucha and more in big glass carboy jugs, including 3, 5 and 6 gallon volumes. The silicone caps stretch to fit over the mouth of the jugs so they can be used with a number of different jug styles universally. Each lid has two tubes that can connect with brewer equipment accessories, like airlocks, siphons, tubing, or racking canes, and also has 2 posts to house white sealing caps so they never go missing when you need them. The white caps can be moved from their hosing stations to cover the opening of the tubes if only one accessory needs to be attached, or to cover both openings to create an airtight seal to replace the use of corks. Each pack includes 4 lids and 8 white caps and is made of top quality silicone that can be washed by hand or in the dishwasher. These Car Boy Airlock Caps are part of the Fermentology suite of products; Fermentology are experts in home fermentation weights, tampers, stoppers and more for wide and regular mouth Mason jars and carry a variety of supplies and kits for fermenting, like waterless airlocks, traditional airlocks.
Airlock-Ready Carboy Caps for Brewing
Each set includes 4 caps that fit over the mouth of carboy jugs to attach fermenting and brewing accessories. Fits 3/5/6 gallon carboy jugs without needing any threading; simply stretches to fit over the mouth of the jug
Never Lose the Caps
Each lid has two housing posts to safely store the caps when not in use, so they’re always there when you need them.
Lids Fit 1 or 2 Accessories
Each lid can be fitted with two fermenting or brewing tools, like airlocks, tubes, siphons, racking canes and more.
Doubles as a Cork
Block off unused pipe openings with sealing caps if only one accessory is needed, or put them both on to create an airtight seal to replace the use of a cork.
Universal Fit for Carboys
The silicone caps have an inner diameter of 49.7mm that can be stretched to fit over the mouth of carboy jugs. The spouts have inner diameters of 9mm and 6mm for inserting brewing equipment into, but can also be stretched to fit larger accessories. Fermentology carboy caps can fit 3, 5 and 6 gallon jugs.
Food Safe, Quality Materials
All Fermentology products are made of food safe and high-quality plastics and silicones. The items included in this box kit are BPA-free and phthalate-free. All of our fermenting equipment is designed in-house by a group of avid fermenters in Toronto, Canada.
Part of a Suite of Fermentation Products
This set is one of many fermentation tools Fermentology has to offer. Our other products include waterless airlocks with pumps, traditional airlocks, fermentation weights, and vegetable tampers. We have equipment for all styles and levels of experience when it comes to lacto fermenting vegetables.
Matt
2025-09-07 11:04:23
I have a random collection of glass and PET carboys with slightly different opening sizes. These fit most and are easy to setup with an airlock. Silicon makes them stretchy and soft.
Jonathan Hicks
2025-09-04 15:05:33
I am an early home brewer and bought these so I wouldn't have to mess with fitting bungs. I couldn't get the right size bung, or it would slip out. This product completely fixed that problem and then some! You can fashion one into a blowoff apparatus if you connect tubing to it, and it works great! I threw away all of the other bungs I had and I use this cap EXCLUSIVELY. I will be buying these from now on.
Whitehorse
2025-08-17 18:46:54
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T. Porter
2025-08-14 12:32:09
These are a lot easier to install and remove than the traditional rubber or silicone bung and seal just as well. I wish they made one for one gallon jugs.
Kaleidoscope
2025-08-10 14:20:00
Trying to reduce my daily exposure to plastics, and this was the only silicon cap I found so far. Bonus opening taps help relieve pressure when trying to close over a jug, and also doubles as water taps if jugs are tipped over carefully with a silicon matt or coaster (avoiding having to buy a plastic tap).
Honest Opinion.
2025-07-23 12:55:04
They seem well made, should last a long time and if they fit my carboys I would have been satisfied! However that was not the case. It's my fault for not breaking out the calipers and measuring the diameter of my bottle opening. I would recommend that you make sure that your carboys are sized to fit these before purchasing. That aside, they're are well made, very functional and I would recommend them without hesitation. Just make sure you use their pictured measurement guide in the product description photos to make sure they fit your carboy. I knocked off 1 star because in the description it states they will fit a 6.5 gallon carboy but they did not fit my Italian made carboy 6.5 gallon. I was able to get them to work using a zip tie. So, not a total loss.
Matt
2025-06-20 15:39:43
I have a random collection of glass and PET carboys with slightly different opening sizes. These fit most and are easy to setup with an airlock. Silicon makes them stretchy and soft.
Jonathan Hicks
2025-06-17 10:49:59
I am an early home brewer and bought these so I wouldn't have to mess with fitting bungs. I couldn't get the right size bung, or it would slip out. This product completely fixed that problem and then some! You can fashion one into a blowoff apparatus if you connect tubing to it, and it works great! I threw away all of the other bungs I had and I use this cap EXCLUSIVELY. I will be buying these from now on.
Whitehorse
2025-06-13 10:58:23
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T. Porter
2025-05-28 16:13:04
These are a lot easier to install and remove than the traditional rubber or silicone bung and seal just as well. I wish they made one for one gallon jugs.
Kaleidoscope
2025-05-26 09:59:51
Trying to reduce my daily exposure to plastics, and this was the only silicon cap I found so far. Bonus opening taps help relieve pressure when trying to close over a jug, and also doubles as water taps if jugs are tipped over carefully with a silicon matt or coaster (avoiding having to buy a plastic tap).
Honest Opinion.
2025-05-25 18:39:45
They seem well made, should last a long time and if they fit my carboys I would have been satisfied! However that was not the case. It's my fault for not breaking out the calipers and measuring the diameter of my bottle opening. I would recommend that you make sure that your carboys are sized to fit these before purchasing. That aside, they're are well made, very functional and I would recommend them without hesitation. Just make sure you use their pictured measurement guide in the product description photos to make sure they fit your carboy. I knocked off 1 star because in the description it states they will fit a 6.5 gallon carboy but they did not fit my Italian made carboy 6.5 gallon. I was able to get them to work using a zip tie. So, not a total loss.
Ana Maria Arias Rivera
2025-05-18 11:11:21
Excelente producto!
Jeanette Moser
2025-05-06 11:26:24
These are a good fit on my 5 gallon carboys work better than the ones that came with them, this is my first wine making adventure and I am leaning so much.
Joseph G
2025-05-04 16:24:58
These silicone carboy caps are excellent, easy to use and provide a tight seal, they stretch and seal around the carboy opening. These caps are a quality product. ​I use them on the 11.5, 19, and 23 liter carboys made in Italy and Mexico , no issues at all. Some wine when it has a little of residual sugar content left may creature pressure and pop caps off the carboys because of the tight fit. In these cases I will then stretch an elastic band around the cap to give it greater holding power.
Edward Tuite
2025-04-17 10:59:42
Good fit on a 20ltr glas bottle
Manuel Meier
2025-03-26 09:57:57
Perfect for Carboy jugs.
Thomas Glaesing
2025-03-21 16:14:37
Bought these and they fit very well on the carboy. Sit in place and don't pop off. I prefer these over any other bung I have. A modern and effective take on cork/hard Silicone bungs.
Integrity2017
2025-03-19 17:09:09
Product meet expectations
Ana Maria Arias Rivera
2025-02-26 13:24:42
Excelente producto!
Jeanette Moser
2025-01-15 17:37:33
These are a good fit on my 5 gallon carboys work better than the ones that came with them, this is my first wine making adventure and I am leaning so much.
Joseph G
2024-12-22 19:03:44
These silicone carboy caps are excellent, easy to use and provide a tight seal, they stretch and seal around the carboy opening. These caps are a quality product. ​I use them on the 11.5, 19, and 23 liter carboys made in Italy and Mexico , no issues at all. Some wine when it has a little of residual sugar content left may creature pressure and pop caps off the carboys because of the tight fit. In these cases I will then stretch an elastic band around the cap to give it greater holding power.
Edward Tuite
2024-12-09 16:06:12
Good fit on a 20ltr glas bottle
Manuel Meier
2024-11-26 16:22:12
Perfect for Carboy jugs.
Thomas Glaesing
2024-11-24 18:19:42
Bought these and they fit very well on the carboy. Sit in place and don't pop off. I prefer these over any other bung I have. A modern and effective take on cork/hard Silicone bungs.
Integrity2017
2024-11-17 10:24:34
Product meet expectations
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