Three piece water filled Cup Airlocks.
This allows the fermentation gasses to escape without pathogens or anything else to come inside and contained the ferment.
We recommend using vodka, alcohol or vinegar or diluted (4:1) in place of water for added protection from pathogens.
Airlock's are the preferred lock for secondary fermenters, as it is possible to monitor the pressure in the fermenter and prevents bottles from exploding.
You can tell when the ferment is complete by the activity of the bubbles escaping. An active ferment creates lots of bubbles. Slows down as the ferment activity slows. Just a few bubbles a second and the ferment has typically used up most of the fermentable sugars. Lack of bubbles shows lack of ferment. Testing with Hydrometer or Refractometer confirms ferment is complete or stuck.
Includes universal stopper. The universal carboy bungs have a generous taper, so they fit standard 3, 5, 6 and 6.5 gallon carboys. It is impossible to push carboy bungs into a carboy. Unlike stoppers, carboy bungs will seal a carboy when they are still wet.