White metal jars caps include plastisol liners and a button in the center highly popular with canning processes. The 70G (70/450/) neck finish size matches a range of glass jars include jelly jars, clear glass mason jars, and more. The plastisol liner installed into the metal jar caps creates a hermetic seal when applied by various heating methods that assist with maintaining a high level of freshness of your products. The button in the center will depress when the seal is activated and will pop up when the seal has been broken as a visual tamper evidence alert. As always, be sure to test all products with these metal jar caps for proper compatibility.