I use cloth or towel lids on milk kefir grains, and tight metal lids on water kefir grains, in glass jars.
The tighter the lid, the fizzier, and no problems with explosions so far.
I have sun tea jars with plastic lids that work great as long as the air can't get out. If it has a pouring spout in the lid gas can escape and it won't be as fizzy.
The jars that commercial jelly comes in have air tight seals and the lids are lined so there is no exposed metal. Same applies to the large jars restaurants throw away that contained pickles and similar items.