#10 Rubber Stopper with 3/8" Drilled Hole | Fits Standard 3, 5, & 6 Gallon Glass Carboys

The #10 Drilled Rubber Stopper is the industry-standard closure for large-scale fermentation vessels. Specifically sized to provide a continuous, airtight seal for 3, 5, 6, and 6.5-gallon glass carboys, this stopper is a critical component for protecting your beer, wine, or cider from oxygen and contaminants during the fermentation process. The pre-drilled 3/8" (approx. 9mm) hole is perfectly sized to accept all standard S-shape and 3-piece plastic airlocks.

Manufactured from high-quality, food-grade BPA-free rubber, this stopper features a tapered design that ensures a "wedged" fit, even if the glass neck has slight manufacturing variances. The resilient rubber construction is designed to maintain its grip and flexibility through hundreds of fermentation cycles and remains resistant to common brewery sanitizers like Star San and IO-Star. Whether you are a professional vintner or a homebrewer, a secure #10 stopper is your first line of defense against spoilage and oxidation.

Why Quality Stoppers Matter: Cheap, low-grade rubber stoppers can "pop out" of the carboy neck due to CO2 pressure or become brittle and crack over time, leading to batch-ruining leaks. Our #10 stoppers are engineered with a high-grip surface texture that stays seated even when the glass is damp with sanitizer. This ensures that the only way for gas to escape your fermenter is through the airlock, maintaining the precise anaerobic environment your yeast needs to thrive.