Used with or without an airlock, this #10 Stopper With Hole is an essential accessory for your plastic carboy.
This #10 Stopper With Hole fits our 3, 5, and 6 gallon plastic carboys. It can be used with an airlock or without, by simply using a #000 solid stopper (FE400) to plug/unplug the hole. Easy to clean and sanitize. Size - 1 11/16" - 2".