Seal your fermenter securely with the Craft a Brew #6.5 Carboy Rubber Stopper, a durable brewing bung designed for 1 gallon fermenters, airlocks, and blow-off tubing setups. This food-safe rubber stopper creates a tight seal during fermentation while supporting proper CO2 release through compatible airlocks or transfer tubing. Designed to fit Craft a Brew 1 gallon glass carboys and the Catalyst Fermentation System lid, this stopper helps maintain a controlled fermentation environment for beer, wine, mead, cider, kombucha, and other fermentation projects.

The pre-drilled 3/8" opening is compatible with standard 3-piece airlocks, Hex Airlocks, and 5/16" transfer tubing for blow-off setups. Its tapered #6.5 sizing helps create a snug fit in compatible fermenters while remaining easy to insert and remove during cleaning and brewing operations.

This replacement brewing stopper is commonly used as a spare or replacement component for homebrewing kits, fermentation systems, and small-batch fermenters. It is compatible with many Craft a Brew fermentation products and reusable across multiple batches with proper cleaning and sanitation.

Widely used by homebrewers and fermenters seeking dependable sealing performance, the Craft a Brew Carboy Rubber Stopper provides a simple and reliable solution for maintaining controlled fermentation conditions.