Mudder Airlock Grommet, Fermenter Lid Grommet Silicone Grommets for Homebrewing, Straws, Airlock, Beer, Mead, Wine, Silicone Bucket Fermenter Lids, 5/8 Inch OD and 3/8 Inch ID (20)

I bought the 100 pack but only 91 came in the box.The measurements weren’t standard. Some were too loose some were too tight for my airlocks (I have 10 airlocks), I had to go through all to fit each airlock with the right grommet. Once fitting was right I was convinced that they were airtight. All in all, 100 grommets for S$9.32 is a very good price!

1/2" hole makes a tighter seal, 5/8 too large gromet goes thru. Otherwise works well.

Giving 3 stars because although the rubber feels sturdy & a ok thickness there is a noticeable smell that cleaning does not dissipate. For the price at the time of writing(100 for $6.99) I would say the airlock grommets are worth it. I can live with the weird smell for the price.1/2 in hole with a spade bit fit this grommet perfectly. Fit my bubblers that I got from amazon also(Twin Bubble Airlock and Carboy Bung (Pack of 2) )

Definitely made of plastic not silicone. Melts immediately upon heat which silicone will not. Also reeks like petroleum. Whatever this is is not food safe and I do not recommend. Also, if you drill a hole in your lid the size suggested, you just ruined your lid as these will fall through. It's sad how terrible Amazon quality control has become. Be careful.

I only give out 1 star (zero, actually) when an item is a complete fail. This is one of them. The neck of the seal is paper thin and will rip every time you attempt to install the seal into a hole. If somebody were to get lucky and the seal did not rip during installation, it surely would when you attempt to stick an airlock into the hole of the seal. These are useless. Do not trust your important fermentation to these things.