Fermentation Airlock & Bored Rubber Bung.
Lets CO² out without letting contamination in.
Just half fill with water and you're good to go.
The Fermentation Airlock is a standard size so fits all Fermenters.
The Bung fits Standard Glass Demijohns.
Bung Size:
Top : 31mm (approx)
Base : 27mm (approx)