Airlock and rubber stopper from Speidel in Germany.
The stopper is conical. It is 44 mm diameter at the top and 37 mm at the bottom.
It has a 17 mm hole drilled for the airlock.
The airlock is oversized to handle larger fermentations, up to about 500 liters.
It is in two parts for easy cleaning.
Suitable for Speidels fermenters and tanks.