A universal soft rubber bung that will fit both airlock styles and offers some advantages over traditional gum rubber stoppers:

- Lip prevents bung from falling into carboy
- Longer taper produces snugger fit and a better seal

Fits 5 and 6 gallon Better Bottles (20L, 25L) and PET Fermenters, 2000 ml Erlenmeyer Flasks and 54L Demi-john; Rubber Stopper sizes 9.5-10.5