Features： ★ Any airlock fit into the grommet ★ Made of super durable and long lasting silicone ★ The silicone grommets will fit both metal and plastic lids ★ These fermenter grommets made it easy to make an air tight hole for an air lock ★ Use the airlock grommet to turn mason jars into drinking bottles ★ Used these grommets to make my own airlock lids for fermenting ★ Best to start with smaller hole and work up to the 1/2 inch hole to insert the airlock grommet Package Including: 12* silicone grommets