Carboy Rubber Stopper

Carboy Rubber Stopper

$1.99
A reusable #6.5 rubber stopper designed to create a secure fermentation seal for 1 gallon carboys, airlocks, and blow-off tubing setups.
  • #6.5 rubber stopper for home fermentation
  • Fits 1 gallon carboys and Catalyst Fermentation System lids
  • Compatible with airlocks and blow-off tubing
  • Pre-drilled 3/8" opening for fermentation accessories
  • Reusable brewing and fermentation component

This rubber stopper is compatible with:

  • 1 gallon glass carboys
  • Craft a Brew 1 gallon kits
  • Extra Fermenter Kit
  • Catalyst Fermentation System lid
  • 3-piece airlocks
  • Hex airlocks
  • 5/16" transfer tubing

The stopper helps create a sealed fermentation environment while allowing CO2 to safely escape through an attached airlock or blow-off tube.

  • #6.5 Carboy Rubber Stopper

This brewing stopper is ideal for:

  • Homebrewers
  • Winemakers
  • Mead makers
  • Hard cider brewers
  • Kombucha brewers
  • Small-batch fermentation setups

To use, insert the stopper into a compatible fermenter opening and attach an airlock or blow-off tube through the pre-drilled center hole.

  • Size: #6.5
  • Material: Food-safe rubber
  • Hole Diameter: 3/8"
  • Compatible With: Airlocks, blow-off tubing, 1 gallon fermenters
  • Reusable: Yes
Carboy Rubber Stopper
$1.99

Frequently Asked Questions

This is a #6.5 rubber stopper designed for compatible 1 gallon fermenters and fermentation systems.

It fits Craft a Brew 1 gallon glass carboys, Extra Fermenter Kits, and the Catalyst Fermentation System lid.

Yes. The pre-drilled 3/8" opening is compatible with standard 3-piece airlocks and Hex Airlocks.

Yes. This stopper is compatible with 5/16" transfer tubing for blow-off setups.

Yes. With proper cleaning and sanitation, the stopper can be reused across multiple fermentation batches.

No. Fermenter openings vary by manufacturer and may require different stopper sizes ranging from #2 to #10.


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