Grommet center hole is 3/8″ and is the standard size for standard Fermentation Airlocks.
Grommets easily insert into 9/16″ lid holes ie 14.2875 mms
Choose between grommet for plastic lids and glass lids i.e fido jar. Hole in plastic lid should be 9/16" (14.29 mms) and hole in glass lid should be 5/8" (15.88mms)
AIRLOCK INFO (3 PIECE SENIOR AIRLOCK)
These three piece devices allow fermentation gases to escape the fermentation jar while not allowing air to enter. They need to be half filled with water.
