If you use these with tin plated steel lids, the grommets will collect water and encourage rust. You should remove them each time you wash the lid. Stainless steel lids don’t have this problem.
Silicone Straw Hole Grommets for Mason Jar Lids 5 Pack
These grommets fit in a 10mm (1cm) hole and reduce it to 8mm. They will fit most of our painted metal or stainless steel straw hole lids. Our solid colored lids and daisy lids have smaller holes so they will not fit those.
We don’t recommend grommets for an 8mm or larger straw (like our Safer Rounded End straws). The straw will push the grommet against the sharp metal and cut through it.
5 grommets per order.
They fit the lids and straws I have, and I love the attatched plug!
Not a super tight fit on the lid but tight enough on the straw that if you try to push the straw into it dry, it tears the ring in half.
A necessary accessory for the metal lids though because they make terrible screeching sounds without these.