The lids are made of tinplate. The tinplate material has good thermal expansion and contraction. When used as a sealing material, the container is vacuum and watertight. But the lid is prone to rusting as the paint wears.Please replace the lid once it becomes rusty. EXCELLENT SEALING: The seal ring in the mason jar lids ensure the preservation has good sealing performance for food preservation. Safe storage. SPLIT DESIGN: Each pack contains 24pcs split lids, convenient for you to replace the lids or rings with durable, safe and sanitary function. The can lids and rings can be replaced separately, which is more economical, meets your various needs. HIGH-QUALITY MATERIALS: The normal mouth mouth jar lids are made of tinplate, which can be reused many times, can withstand high and low temperatures, can be used in refrigerators, microwave ovens and dishwashers; Our glass rings can be used with most brands of mason bottles. MULTIPLE USAGE: Suitable for sealing the mason jars that stored spices, candy, biscuits, fruits, jams, soft drinks, tea or coffee, nails, screws and other small items. A NOTICE: Please make sure the size before purchasing. Material: Tinplate Size: 70mm / 2.8in Color: Silver Package: 24 Pcs x Mason Jar Lids