Foam Stopper for Erlenmeyer Flask

Keep your yeast starters clean and protected with the Foam Stopper for Erlenmeyer Flasks, designed to allow proper airflow while blocking dust, debris, and contaminants. This heat-resistant, breathable stopper fits both 1000 mL and 2000 mL flasks, making it ideal for homebrewers who prepare yeast starters directly on a stir plate or during boil sterilization. The open-cell foam structure maintains gas exchange so yeast can grow efficiently, while preventing airborne particles from entering the flask during cooling or active fermentation. Its high temperature tolerance allows the stopper to remain in place through boiling and rapid temperature changes without degrading or losing shape. Sized to fit standard borosilicate Erlenmeyer flasks, the stopper offers a reusable, easy-to-clean solution that replaces foil or loose-fitting lids. It supports consistent starter preparation by promoting healthy cell growth and reducing contamination risk at every stage. Widely used by home and professi